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spectrochempy.Coord¶

class Coord(data=None, **kwargs)[source]¶

Explicit coordinates for a dataset along a given axis.

The coordinates of a NDDataset can be created using the Coord object. This is a single dimension array with either numerical (float) values or labels (str, Datetime objects, or any other kind of objects) to represent the coordinates. Only a one numerical axis can be defined, but labels can be multiple.

Parameters

data (ndarray, tuple or list) – The actual data array contained in the Coord object. The given array (with a single dimension) can be a list, a tuple, a ndarray , or a array-like object. If an object is passed that contains labels, or units, these elements will be used to accordingly set those of the created object. If possible, the provided data will not be copied for data input, but will be passed by reference, so you should make a copy the data before passing it in the object constructor if that’s the desired behavior or set the copy argument to True.
**kwargs – Optional keywords parameters. See other parameters.

Other Parameters

dtype (str or dtype, optional, default=np.float64) – If specified, the data will be cast to this dtype, else the type of the data will be used.
dims (list of chars, optional.) – if specified the list must have a length equal to the number od data dimensions (ndim) and the chars must be taken among x,y,z,u,v,w or t. If not specified, the dimension names are automatically attributed in this order.
name (str, optional) – A user-friendly name for this object. If not given, the automatic id given at the object creation will be used as a name.
labels (array of objects, optional) – Labels for the data . labels can be used only for 1D-datasets. The labels array may have an additional dimension, meaning several series of labels for the same data. The given array can be a list, a tuple, a ndarray , a ndarray-like, a NDArray or any subclass of NDArray .
units (Unit instance or str, optional) – Units of the data. If data is a Quantity then units is set to the unit of the data; if a unit is also explicitly provided an error is raised. Handling of units use the pint package.
title (str, optional) – The title of the dimension. It will later be used for instance for labelling plots of the data. It is optional but recommended to give a title to each ndarray.
dlabel (str, optional) – Alias of title .
linearize_below (float, optional, default=0.1) – variation of spacing in % below which the coordinate is linearized. Set it to
rounding (bool, optional, default=True) – If True, the data will be rounded to the number of significant digits given by sigdigits.
sigdigits (int, optional, default=4) – Number of significant digits to be used for rounding and linearizing the data.
larmor (float or Quantity instance, optional) – The Larmor frequency of the nucleus. This is used only for NMR data.
offset (float instance, optional) – The offset of the axis. This is used to generate an evenly values spaced axis together with ìncrement and size.
increment (float instance, optional) – The increment between two consecutive values of the axis. This is used to generate an evenly values spaced axis together with offset and size.
size (int instance, optional) – The size of the axis. This is used to generate an evenly values spaced axis together with offset and increment.

See also

NDDataset: Main SpectroChemPy object: an array with masks, units and coordinates.

Examples

We first import the object from the api :

>>> from spectrochempy import Coord

We then create a numpy ndarray and use it as the numerical data axis of our new Coord object :

>>> c0 = Coord.arange(1., 12., 2., title='frequency', units='Hz')
>>> c0
Coord: [float64] Hz (size: 6)

We can take a series of str to create a non-numerical but labelled axis :

>>> tarr = list('abcdef')
>>> tarr
['a', 'b', 'c', 'd', 'e', 'f']

>>> c1 = Coord(labels=tarr, title='mylabels')
>>> c1
Coord: [labels] [  a   b   c   d   e   f] (size: 6)

Attributes Summary

`data`	Data array (`ndarray`).
`dimensionless`	True if the `data` array is dimensionless - Readonly property (bool).
`dtype`	Return the data type.
`filename`	Current filename for this dataset (`Pathlib` object).
`has_data`	True if the `data` array is not empty.
`has_defined_name`	True is the name has been defined (bool).
`has_units`	True if the `data` array have units - Readonly property (bool).
`id`	Object identifier - Readonly property (str).
`is_empty`	True if the `data` array is empty or size=0, and if no label are present.
`is_float`	True if the `data` are real values - Readonly property (bool).
`is_integer`	True if the `data` are integer values - Readonly property (bool).
`is_labeled`	True if the `data` array have labels - Readonly property (bool).
`labels`	An array of labels for `data` (`ndarray` of str).
`larmor`	Return larmor frequency in NMR spectroscopy context.
`laser_frequency`	Laser frequency if needed (Quantity).
`limits`	Range of the data (list).
`linear`	Whether the coordinates axis is linear (i.e.
`m`	Data array (`ndarray`).
`magnitude`	Data array (`ndarray`).
`meta`	Additional metadata (`Meta`).
`name`	A user-friendly name (str).
`reversed`	Whether the axis is reversed.
`roi`	Region of interest (ROI) limits (list).
`shape`	A tuple with the size of each dimension - Readonly property.
`show_datapoints`	True if axis must discard values and show only datapoints.
`sigdigits`	Number of significant digits for rounding coordinate values.
`size`	Size of the underlying `data` array - Readonly property (int).
`spacing`	Coordinate spacing.
`title`	An user-friendly title (str).
`umasked_data`	The actual array with mask and unit (`Quantity`).
`unitless`	`bool` - True if the `data` does not have `units` (Readonly property).
`units`	`Unit` - The units of the data.
`value`	Alias of `values` .
`values`	`Quantity` - The actual values (data, units) contained in this object (Readonly property).

Methods Summary

`amax`(dataset[, dim, keepdims])	Return the maximum of the dataset or maxima along given dimensions.
`amin`(dataset[, dim, keepdims])	Return the maximum of the dataset or maxima along given dimensions.
`arange`([start, stop, step, dtype])	Return evenly spaced values within a given interval.
`around`(dataset[, decimals])	Evenly round to the given number of decimals.
`astype`([dtype])	Cast the data to a specified type.
`copy`([deep, keepname])	Make a disconnected copy of the current object.
`fromfunction`(cls, function[, shape, dtype, ...])	Construct a nddataset by executing a function over each coordinate.
`fromiter`(iterable[, dtype, count])	Create a new 1-dimensional array from an iterable object.
`geomspace`(start, stop[, num, endpoint, dtype])	Return numbers spaced evenly on a log scale (a geometric progression).
`get_labels`([level])	Get the labels at a given level.
`is_units_compatible`(other)	Check the compatibility of units with another object.
`ito`(other[, force])	Inplace scaling to different units.
`ito_base_units`()	Inplace rescaling to base units.
`ito_reduced_units`()	Quantity scaled in place to reduced units, inplace.
`linearize`([sigdigits])	Linearize the coordinate's data.
`linspace`(cls, start, stop[, num, endpoint, ...])	Return evenly spaced numbers over a specified interval.
`loc2index`(loc[, return_error])	Return the index corresponding to a given location.
`logspace`(cls, start, stop[, num, endpoint, ...])	Return numbers spaced evenly on a log scale.
`max`(dataset[, dim, keepdims])	Return the maximum of the dataset or maxima along given dimensions.
`min`(dataset[, dim, keepdims])	Return the maximum of the dataset or maxima along given dimensions.
`ptp`(dataset[, dim, keepdims])	Range of values (maximum - minimum) along a dimension.
`round`(dataset[, decimals])	Evenly round to the given number of decimals.
`round_`(dataset[, decimals])	Evenly round to the given number of decimals.
`set_laser_frequency`([frequency])	Set the laser frequency.
`to`(other[, inplace, force])	Return the object with data rescaled to different units.
`to_base_units`([inplace])	Return an array rescaled to base units.
`to_reduced_units`([inplace])	Return an array scaled in place to reduced units.

Attributes Documentation

data¶

Data array (ndarray).

If there is no data but labels, then the labels are returned instead of data.

Notes

The data are always returned as a 1D array of float rounded to the number of significant digits given by the sigdigits parameters. If the spacing between the data is constant with the accuracy given by the significant digits, the data are thus linearized and the linear attribute is set to True.

dimensionless¶

True if the data array is dimensionless - Readonly property (bool).

See also

unitless: True if data has no units.
has_units: True if data has units.

Notes

Dimensionless is different of unitless which means no unit.

dtype¶: Return the data type.

filename¶: Current filename for this dataset (Pathlib object).

has_data¶: True if the data array is not empty.

has_defined_name¶: True is the name has been defined (bool).

has_units¶

True if the data array have units - Readonly property (bool).

See also

unitless: True if the data has no unit.
dimensionless: True if the data have dimensionless units.

id¶: Object identifier - Readonly property (str).

is_empty¶

True if the data array is empty or size=0, and if no label are present.

Readonly property (bool).

is_float¶: True if the data are real values - Readonly property (bool).

is_integer¶: True if the data are integer values - Readonly property (bool).

is_labeled¶: True if the data array have labels - Readonly property (bool).

labels¶

An array of labels for data (ndarray of str).

An array of objects of any type (but most generally string), with the last dimension size equal to that of the dimension of data. Note that’s labelling is possible only for 1D data. One classical application is the labelling of coordinates to display informative strings instead of numerical values.

larmor¶: Return larmor frequency in NMR spectroscopy context.

laser_frequency¶: Laser frequency if needed (Quantity).

limits¶: Range of the data (list).

linear¶: Whether the coordinates axis is linear (i.e. regularly spaced)

m¶

Data array (ndarray).

If there is no data but labels, then the labels are returned instead of data.

magnitude¶

Data array (ndarray).

If there is no data but labels, then the labels are returned instead of data.

meta¶: Additional metadata (Meta).

name¶

A user-friendly name (str).

When no name is provided, the id of the object is returned instead.

reversed¶: Whether the axis is reversed.

roi¶: Region of interest (ROI) limits (list).

shape¶

A tuple with the size of each dimension - Readonly property.

The number of data element on each dimension (possibly complex). For only labelled array, there is no data, so it is the 1D and the size is the size of the array of labels.

show_datapoints¶

True if axis must discard values and show only datapoints.

Type: Bool

sigdigits¶: Number of significant digits for rounding coordinate values.

Note

The number of significant digits is used when linearizing the coordinates. It is also used when setting the coordinates values at the Coord initialization or everytime the data array is changed.

size¶

Size of the underlying data array - Readonly property (int).

The total number of data elements (possibly complex or hypercomplex in the array).

spacing¶

Coordinate spacing.

It will be a scalar if the coordinates are uniformly spaced, else an array of the different spacings.

Note

The spacing is returned in the units of the coordinate.

title¶

An user-friendly title (str).

When the title is provided, it can be used for labeling the object, e.g., axe title in a matplotlib plot.

umasked_data¶

The actual array with mask and unit (Quantity).

(Readonly property).

unitless¶: bool - True if the data does not have units (Readonly property).

units¶: Unit - The units of the data.

value¶: Alias of values .

values¶: Quantity - The actual values (data, units) contained in this object (Readonly property).

Methods Documentation

amax(dataset, dim=None, keepdims=False, **kwargs)[source]¶

Return the maximum of the dataset or maxima along given dimensions.

Parameters

dataset (array_like) – Input array or object that can be converted to an array.
dim (None or int or dimension name or tuple of int or dimensions, optional) – Dimension or dimensions along which to operate. By default, flattened input is used. If this is a tuple, the maximum is selected over multiple dimensions, instead of a single dimension or all the dimensions as before.
keepdims (bool, optional) – If this is set to True, the axes which are reduced are left in the result as dimensions with size one. With this option, the result will broadcast correctly against the input array.

Returns

amax – Maximum of the data. If dim is None, the result is a scalar value. If dim is given, the result is an array of dimension ndim - 1 .

See also

amin: The minimum value of a dataset along a given dimension, propagating NaNs.
minimum: Element-wise minimum of two datasets, propagating any NaNs.
maximum: Element-wise maximum of two datasets, propagating any NaNs.
fmax: Element-wise maximum of two datasets, ignoring any NaNs.
fmin: Element-wise minimum of two datasets, ignoring any NaNs.
argmax: Return the indices or coordinates of the maximum values.
argmin: Return the indices or coordinates of the minimum values.

Notes

For dataset with complex or hypercomplex type type, the default is the value with the maximum real part.

amin(dataset, dim=None, keepdims=False, **kwargs)[source]¶

Return the maximum of the dataset or maxima along given dimensions.

Parameters

dataset (array_like) – Input array or object that can be converted to an array.
dim (None or int or dimension name or tuple of int or dimensions, optional) – Dimension or dimensions along which to operate. By default, flattened input is used. If this is a tuple, the minimum is selected over multiple dimensions, instead of a single dimension or all the dimensions as before.
keepdims (bool, optional) – If this is set to True, the dimensions which are reduced are left in the result as dimensions with size one. With this option, the result will broadcast correctly against the input array.

Returns

amin – Minimum of the data. If dim is None, the result is a scalar value. If dim is given, the result is an array of dimension ndim - 1 .

See also

amax: The maximum value of a dataset along a given dimension, propagating NaNs.
minimum: Element-wise minimum of two datasets, propagating any NaNs.
maximum: Element-wise maximum of two datasets, propagating any NaNs.
fmax: Element-wise maximum of two datasets, ignoring any NaNs.
fmin: Element-wise minimum of two datasets, ignoring any NaNs.
argmax: Return the indices or coordinates of the maximum values.
argmin: Return the indices or coordinates of the minimum values.

arange(start=0, stop=None, step=None, dtype=None, **kwargs)[source]¶

Return evenly spaced values within a given interval.

Values are generated within the half-open interval [start, stop).

Parameters

start (number, optional) – Start of interval. The interval includes this value. The default start value is 0.
stop (number) – End of interval. The interval does not include this value, except in some cases where step is not an integer and floating point round-off affects the length of out. It might be prefereble to use inspace in such case.
step (number, optional) – Spacing between values. For any output out, this is the distance between two adjacent values, out[i+1] - out[i]. The default step size is 1. If step is specified as a position argument, start must also be given.
dtype (dtype) – The type of the output array. If dtype is not given, infer the data type from the other input arguments.
**kwargs – Keywords argument used when creating the returned object, such as units, name, title, …

Returns

arange – Array of evenly spaced values.

See also

linspace: Evenly spaced numbers with careful handling of endpoints.

Examples

>>> scp.arange(1, 20.0001, 1, units='s', name='mycoord')
NDDataset: [float64] s (size: 20)

around(dataset, decimals=0)[source]¶

Evenly round to the given number of decimals.

Parameters

dataset (NDDataset) – Input dataset.
decimals (int, optional) – Number of decimal places to round to (default: 0). If decimals is negative, it specifies the number of positions to the left of the decimal point.

Returns

rounded_array – NDDataset containing the rounded values. The real and imaginary parts of complex numbers are rounded separately. The result of rounding a float is a float. If the dataset contains masked data, the mask remain unchanged.

See also

numpy.round, around, spectrochempy.round, spectrochempy.around, methods., ceil, fix, floor, rint, trunc

astype(dtype=None, **kwargs)[source]¶

Cast the data to a specified type.

Parameters: dtype (str or dtype) – Typecode or data-type to which the array is cast.

copy(deep=True, keepname=False, **kwargs)[source]¶

Make a disconnected copy of the current object.

Parameters

deep (bool, optional) – If True a deepcopy is performed which is the default behavior.
keepname (bool) – If True keep the same name for the copied object.

Returns

object – An exact copy of the current object.

Examples

>>> nd1 = scp.NDArray([1. + 2.j, 2. + 3.j])
>>> nd1
NDArray: [complex128] unitless (size: 2)
>>> nd2 = nd1
>>> nd2 is nd1
True
>>> nd3 = nd1.copy()
>>> nd3 is not nd1
True

fromfunction(cls, function, shape=None, dtype=float, units=None, coordset=None, **kwargs)[source]¶

Construct a nddataset by executing a function over each coordinate.

The resulting array therefore has a value fn(x, y, z) at coordinate (x, y, z) .

Parameters

function (callable) – The function is called with N parameters, where N is the rank of shape or from the provided CoordSet .
shape ((N,) tuple of ints, optional) – Shape of the output array, which also determines the shape of the coordinate arrays passed to function . It is optional only if CoordSet is None.
dtype (data-type, optional) – Data-type of the coordinate arrays passed to function . By default, dtype is float.
units (str, optional) – Dataset units. When None, units will be determined from the function results.
coordset (CoordSet instance, optional) – If provided, this determine the shape and coordinates of each dimension of the returned NDDataset . If shape is also passed it will be ignored.
**kwargs – Other kwargs are passed to the final object constructor.

Returns

fromfunction – The result of the call to function is passed back directly. Therefore the shape of fromfunction is completely determined by function .

See also

fromiter: Make a dataset from an iterable.

Examples

Create a 1D NDDataset from a function

>>> func1 = lambda t, v: v * t
>>> time = scp.Coord.arange(0, 60, 10, units='min')
>>> d = scp.fromfunction(func1, v=scp.Quantity(134, 'km/hour'), coordset=scp.CoordSet(t=time))
>>> d.dims
['t']
>>> d
NDDataset: [float64] km (size: 6)

fromiter(iterable, dtype=np.float64, count=-1, **kwargs)[source]¶

Create a new 1-dimensional array from an iterable object.

Parameters

iterable (iterable object) – An iterable object providing data for the array.
dtype (data-type) – The data-type of the returned array.
count (int, optional) – The number of items to read from iterable. The default is -1, which means all data is read.
**kwargs – Other kwargs are passed to the final object constructor.

Returns

fromiter – The output nddataset.

See also

fromfunction: Construct a nddataset by executing a function over each coordinate.

Notes

Specify count to improve performance. It allows fromiter to pre-allocate the: output array, instead of resizing it on demand.

Examples

>>> iterable = (x * x for x in range(5))
>>> d = scp.fromiter(iterable, float, units='km')
>>> d
NDDataset: [float64] km (size: 5)
>>> d.data
array([       0,        1,        4,        9,       16])

geomspace(start, stop, num=50, endpoint=True, dtype=None, **kwargs)[source]¶

Return numbers spaced evenly on a log scale (a geometric progression).

This is similar to logspace , but with endpoints specified directly. Each output sample is a constant multiple of the previous.

Parameters

start (number) – The starting value of the sequence.
stop (number) – The final value of the sequence, unless endpoint is False. In that case, num + 1 values are spaced over the interval in log-space, of which all but the last (a sequence of length num ) are returned.
num (int, optional) – Number of samples to generate. Default is 50.
endpoint (bool, optional) – If true, stop is the last sample. Otherwise, it is not included. Default is True.
dtype (dtype) – The type of the output array. If dtype is not given, infer the data type from the other input arguments.
**kwargs – Keywords argument used when creating the returned object, such as units, name, title, …

Returns

geomspace – num samples, equally spaced on a log scale.

See also

logspace: Similar to geomspace, but with endpoints specified using log and base.
linspace: Similar to geomspace, but with arithmetic instead of geometric progression.
arange: Similar to linspace, with the step size specified instead of the number of samples.

get_labels(level=0)[source]¶

Get the labels at a given level.

Used to replace data when only labels are provided, and/or for labeling axis in plots.

Parameters: level (int, optional, default:0) – Label level.
Returns: ndarray – The labels at the desired level or None.

is_units_compatible(other)[source]¶

Check the compatibility of units with another object.

Parameters: other (ndarray) – The ndarray object for which we want to compare units compatibility.
Returns: result – True if units are compatible.

Examples

>>> nd1 = scp.NDDataset([1. + 2.j, 2. + 3.j], units='meters')
>>> nd1
NDDataset: [complex128] m (size: 2)
>>> nd2 = scp.NDDataset([1. + 2.j, 2. + 3.j], units='seconds')
>>> nd1.is_units_compatible(nd2)
False
>>> nd1.ito('minutes', force=True)
>>> nd1.is_units_compatible(nd2)
True
>>> nd2[0].values * 60. == nd1[0].values
True

ito(other, force=False)[source]¶

Inplace scaling to different units. (same as to with inplace= True).

Parameters

other (Unit , Quantity or str) – Destination units.
force (bool, optional, default=`False`) – If True the change of units is forced, even for incompatible units.

See also

to: Rescaling of the current object data to different units.
to_base_units: Rescaling of the current object data to different units.
ito_base_units: Inplace rescaling of the current object data to different units.
to_reduced_units: Rescaling to reduced units.
ito_reduced_units: Rescaling to reduced units.

ito_base_units()[source]¶

Inplace rescaling to base units.

See also

to: Rescaling of the current object data to different units.
ito: Inplace rescaling of the current object data to different units.
to_base_units: Rescaling of the current object data to different units.
to_reduced_units: Rescaling to redunced units.
ito_reduced_units: Inplace rescaling to reduced units.

ito_reduced_units()[source]¶

Quantity scaled in place to reduced units, inplace.

Scaling to reduced units means one unit per dimension. This will not reduce compound units (e.g., ‘J/kg’ will not be reduced to m**2/s**2).

See also

to: Rescaling of the current object data to different units.
ito: Inplace rescaling of the current object data to different units.
to_base_units: Rescaling of the current object data to different units.
ito_base_units: Inplace rescaling of the current object data to different units.
to_reduced_units: Rescaling to reduced units.

linearize(sigdigits=4)[source]¶

Linearize the coordinate’s data.

Make coordinates with an equally distributed spacing, when possible, i.e., if the spacings are not too different when rounded to the number of significant digits passed in parameters. If the spacings are too different, the coordinates are not linearized. In this case, the linear attribute is set to False.

Parameters: sigdigits (Int, optional, default=4) – The number of significant digit for coordinates values.

linspace(cls, start, stop, num=50, endpoint=True, retstep=False, dtype=None, **kwargs)[source]¶

Return evenly spaced numbers over a specified interval.

Returns num evenly spaced samples, calculated over the interval [start, stop]. The endpoint of the interval can optionally be excluded.

Parameters

start (array_like) – The starting value of the sequence.
stop (array_like) – The end value of the sequence, unless endpoint is set to False. In that case, the sequence consists of all but the last of num + 1 evenly spaced samples, so that stop is excluded. Note that the step size changes when endpoint is False.
num (int, optional) – Number of samples to generate. Default is 50. Must be non-negative.
endpoint (bool, optional) – If True, stop is the last sample. Otherwise, it is not included. Default is True.
retstep (bool, optional) – If True, return (samples, step), where step is the spacing between samples.
dtype (dtype, optional) – The type of the array. If dtype is not given, infer the data type from the other input arguments.
**kwargs – Keywords argument used when creating the returned object, such as units,

name, title, …

Returns

linspace (ndarray) – There are num equally spaced samples in the closed interval [start, stop] or the half-open interval [start, stop) (depending on whether endpoint is True or False).
step (float, optional) – Only returned if retstep is True Size of spacing between samples.

loc2index(loc, return_error=False)[source]¶

Return the index corresponding to a given location.

Parameters: loc (float.) – Value corresponding to a given location on the coordinates axis.
Returns: index (int.) – The corresponding index.

Examples

>>> dataset = scp.read("irdata/nh4y-activation.spg")
>>> dataset.x.loc2index(1644.0)
4517

logspace(cls, start, stop, num=50, endpoint=True, base=10.0, dtype=None, **kwargs)[source]¶

Return numbers spaced evenly on a log scale.

In linear space, the sequence starts at base ** start (base to the power of start ) and ends with base ** stop (see endpoint below).

Parameters

start (array_like) – base ** start is the starting value of the sequence.
stop (array_like) – base ** stop is the final value of the sequence, unless endpoint is False. In that case, num + 1 values are spaced over the interval in log-space, of which all but the last (a sequence of length num ) are returned.
num (int, optional) – Number of samples to generate. Default is 50.
endpoint (bool, optional) – If true, stop is the last sample. Otherwise, it is not included. Default is True.
base (float, optional) – The base of the log space. The step size between the elements in ln(samples) / ln(base) (or log_base(samples) ) is uniform. Default is 10.0.
dtype (dtype) – The type of the output array. If dtype is not given, infer the data type from the other input arguments.
**kwargs – Keywords argument used when creating the returned object, such as units, name, title, …

Returns

logspace – num samples, equally spaced on a log scale.

See also

arange: Similar to linspace, with the step size specified instead of the number of samples. Note that, when used with a float endpoint, the endpoint may or may not be included.
linspace: Similar to logspace, but with the samples uniformly distributed in linear space, instead of log space.
geomspace: Similar to logspace, but with endpoints specified directly.

max(dataset, dim=None, keepdims=False, **kwargs)[source]¶

Return the maximum of the dataset or maxima along given dimensions.

Parameters

dataset (array_like) – Input array or object that can be converted to an array.
dim (None or int or dimension name or tuple of int or dimensions, optional) – Dimension or dimensions along which to operate. By default, flattened input is used. If this is a tuple, the maximum is selected over multiple dimensions, instead of a single dimension or all the dimensions as before.
keepdims (bool, optional) – If this is set to True, the axes which are reduced are left in the result as dimensions with size one. With this option, the result will broadcast correctly against the input array.

Returns

amax – Maximum of the data. If dim is None, the result is a scalar value. If dim is given, the result is an array of dimension ndim - 1 .

See also

amin: The minimum value of a dataset along a given dimension, propagating NaNs.
minimum: Element-wise minimum of two datasets, propagating any NaNs.
maximum: Element-wise maximum of two datasets, propagating any NaNs.
fmax: Element-wise maximum of two datasets, ignoring any NaNs.
fmin: Element-wise minimum of two datasets, ignoring any NaNs.
argmax: Return the indices or coordinates of the maximum values.
argmin: Return the indices or coordinates of the minimum values.

Notes

For dataset with complex or hypercomplex type type, the default is the value with the maximum real part.

min(dataset, dim=None, keepdims=False, **kwargs)[source]¶

Return the maximum of the dataset or maxima along given dimensions.

Parameters

dataset (array_like) – Input array or object that can be converted to an array.
dim (None or int or dimension name or tuple of int or dimensions, optional) – Dimension or dimensions along which to operate. By default, flattened input is used. If this is a tuple, the minimum is selected over multiple dimensions, instead of a single dimension or all the dimensions as before.
keepdims (bool, optional) – If this is set to True, the dimensions which are reduced are left in the result as dimensions with size one. With this option, the result will broadcast correctly against the input array.

Returns

amin – Minimum of the data. If dim is None, the result is a scalar value. If dim is given, the result is an array of dimension ndim - 1 .

See also

amax: The maximum value of a dataset along a given dimension, propagating NaNs.
minimum: Element-wise minimum of two datasets, propagating any NaNs.
maximum: Element-wise maximum of two datasets, propagating any NaNs.
fmax: Element-wise maximum of two datasets, ignoring any NaNs.
fmin: Element-wise minimum of two datasets, ignoring any NaNs.
argmax: Return the indices or coordinates of the maximum values.
argmin: Return the indices or coordinates of the minimum values.

ptp(dataset, dim=None, keepdims=False)[source]¶

Range of values (maximum - minimum) along a dimension.

The name of the function comes from the acronym for ‘peak to peak’ .

Parameters

dim (None or int or dimension name, optional) – Dimension along which to find the peaks. If None, the operation is made on the first dimension.
keepdims (bool, optional) – If this is set to True, the dimensions which are reduced are left in the result as dimensions with size one. With this option, the result will broadcast correctly against the input dataset.

Returns

ptp – A new dataset holding the result.

round(dataset, decimals=0)[source]¶

Evenly round to the given number of decimals.

Parameters

dataset (NDDataset) – Input dataset.
decimals (int, optional) – Number of decimal places to round to (default: 0). If decimals is negative, it specifies the number of positions to the left of the decimal point.

Returns

rounded_array – NDDataset containing the rounded values. The real and imaginary parts of complex numbers are rounded separately. The result of rounding a float is a float. If the dataset contains masked data, the mask remain unchanged.

See also

numpy.round, around, spectrochempy.round, spectrochempy.around, methods., ceil, fix, floor, rint, trunc

round_(dataset, decimals=0)[source]¶

Evenly round to the given number of decimals.

Parameters

dataset (NDDataset) – Input dataset.
decimals (int, optional) – Number of decimal places to round to (default: 0). If decimals is negative, it specifies the number of positions to the left of the decimal point.

Returns

rounded_array – NDDataset containing the rounded values. The real and imaginary parts of complex numbers are rounded separately. The result of rounding a float is a float. If the dataset contains masked data, the mask remain unchanged.

See also

numpy.round, around, spectrochempy.round, spectrochempy.around, methods., ceil, fix, floor, rint, trunc

set_laser_frequency(frequency=15798.26 * ur('cm^-1'))[source]¶

Set the laser frequency.

This method is used to set the laser frequency of the dataset. The laser frequency is used to convert the x-axis from optical path difference to time. The laser frequency is also used to calculate the wavenumber axis.

Parameters: frequency (float or Quantity, optional, default=15798.26 * ur(“cm^-1”)) – The laser frequency in cm^-1 or Hz. If the value is in cm^-1, the frequency is converted to Hz using the current speed of light value.

to(other, inplace=False, force=False)[source]¶

Return the object with data rescaled to different units.

Parameters

other (Quantity or str) – Destination units.
inplace (bool, optional, default=`False`) – Flag to say that the method return a new object (default) or not (inplace=True).
force (bool, optional, default=False) – If True the change of units is forced, even for incompatible units.

Returns

rescaled

See also

ito: Inplace rescaling of the current object data to different units.
to_base_units: Rescaling of the current object data to different units.
ito_base_units: Inplace rescaling of the current object data to different units.
to_reduced_units: Rescaling to reduced_units.
ito_reduced_units: Inplace rescaling to reduced units.

Examples

>>> np.random.seed(12345)
>>> ndd = scp.NDArray(data=np.random.random((3, 3)),
...                   mask=[[True, False, False],
...                         [False, True, False],
...                         [False, False, True]],
...                   units='meters')
>>> print(ndd)
NDArray: [float64] m (shape: (y:3, x:3))

We want to change the units to seconds for instance but there is no relation with meters, so an error is generated during the change

>>> ndd.to('second')
Traceback (most recent call last):
...
pint.errors.DimensionalityError: Cannot convert from 'meter' ([length]) to
'second' ([time])

However, we can force the change

>>> ndd.to('second', force=True)
NDArray: [float64] s (shape: (y:3, x:3))

By default the conversion is not done inplace, so the original is not modified :

>>> print(ndd)
NDArray: [float64] m (shape: (y:3, x:3))

to_base_units(inplace=False)[source]¶

Return an array rescaled to base units.

Parameters: inplace (bool) – If True the rescaling is done in place.
Returns: rescaled – A rescaled array.

to_reduced_units(inplace=False)[source]¶

Return an array scaled in place to reduced units.

Reduced units means one unit per dimension. This will not reduce compound units (e.g., ‘J/kg’ will not be reduced to m**2/s**2).

Parameters: inplace (bool) – If True the rescaling is done in place.
Returns: rescaled – A rescaled array.

Examples using spectrochempy.Coord

NDDataset creation and plotting example

NDDataset coordinates example

Units manipulation examples

Loading an IR (omnic SPG) experimental file

Analysis CP NMR spectra

EFA example

EFA (Keller and Massart original example)

2D-IRIS analysis example

MCR-ALS with kinetic constraints

Solve a linear equation using LSTSQ