* New module: wpylib.array_tools for convenient array manipulations.

Wirawan Purwanto 10 years ago
parent 8da8937009
commit a0d8ed87a3
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# Created: 20140207
# Wirawan Purwanto
Various tools for arrays (mainly, numpy array objects).
def array_indices_cond_1d(arr, cond):
"""Get the odered list of array indices whose corresponding elements satisfy
a given condition.
Useful for conditional assignment or evaluation.
The input `cond' argument can be an ufunc-like function that evaluates
a logical expression in bulk for each of the arr's element.
Or it can be an array of logical values that has the same length as arr.
Example use case:
r = numpy.linspace(1.97, 3.5, num=150)
i_select = cond_indices_1d(r, r <= 2.5)
# ... then we can do something with r[i_select]
# for conditional assignment or value extraction.
arr = numpy.asarray(arr)
assert len(arr.shape) == 1
if callable(cond):
cond = cond(arr)
# otherwise, assume cond is already a good array
return numpy.array(xrange(len(arr)))[ cond ]