dask.array.compress

dask.array.compress(condition, a, axis=None)[source]

Return selected slices of an array along given axis.

This docstring was copied from numpy.compress.

Some inconsistencies with the Dask version may exist.

When working along a given axis, a slice along that axis is returned in output for each index where condition evaluates to True. When working on a 1-D array, compress is equivalent to extract.

Parameters
condition1-D array of bools

Array that selects which entries to return. If len(condition) is less than the size of a along the given axis, then output is truncated to the length of the condition array.

aarray_like

Array from which to extract a part.

axisint, optional

Axis along which to take slices. If None (default), work on the flattened array.

outndarray, optional (Not supported in Dask)

Output array. Its type is preserved and it must be of the right shape to hold the output.

Returns
compressed_arrayndarray

A copy of a without the slices along axis for which condition is false.

See also

take, choose, diag, diagonal, select
ndarray.compress

Equivalent method in ndarray

extract

Equivalent method when working on 1-D arrays

Output type determination

Examples

>>> a = np.array([[1, 2], [3, 4], [5, 6]])  
>>> a  
array([[1, 2],
       [3, 4],
       [5, 6]])
>>> np.compress([0, 1], a, axis=0)  
array([[3, 4]])
>>> np.compress([False, True, True], a, axis=0)  
array([[3, 4],
       [5, 6]])
>>> np.compress([False, True], a, axis=1)  
array([[2],
       [4],
       [6]])

Working on the flattened array does not return slices along an axis but selects elements.

>>> np.compress([False, True], a)  
array([2])