/usr/lib/python3/dist-packages/pydl/rebin.py is in python3-pydl 0.6.0-1.
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# -*- coding: utf-8 -*-
from __future__ import division
def rebin(x, d, sample=False):
"""Resize `x` to new dimensions given by `d`. The new dimensions must
be integer multiples or factors of the original dimensions.
Although there are some elegant solutions out there for rebinning, this
function is intended to replace the IDL ``REBIN()`` function, which
has a number of special properties:
* It refuses to perform extrapolation when rebinning to a larger size
in a particular dimension.
* It can simultaneously rebin to a larger size in one dimension while
rebinning to a smaller size in another dimension.
Parameters
----------
x : :class:`~numpy.ndarray`
The array to resample.
d : :func:`tuple`
The new shape of the array.
sample : :class:`bool`, optional
If ``True``, nearest-neighbor techniques will be used instead of
interpolation.
Returns
-------
:class:`~numpy.ndarray`
The resampled array.
Raises
------
ValueError
If the new dimensions are incompatible with the algorithm.
References
----------
http://www.exelisvis.com/docs/REBIN.html
Examples
--------
>>> from numpy import arange, float
>>> from pydl import rebin
>>> rebin(arange(10, dtype=float), (5,))
array([ 0.5, 2.5, 4.5, 6.5, 8.5])
>>> rebin(arange(5, dtype=float), (10,))
array([ 0. , 0.5, 1. , 1.5, 2. , 2.5, 3. , 3.5, 4. , 4. ])
"""
from numpy import floor, zeros
d0 = x.shape
if len(d0) != len(d):
raise ValueError(("The new shape is incompatible with the " +
"original array.!"))
for k in range(len(d0)):
if d[k] > d0[k]:
if d[k] % d0[k] != 0:
raise ValueError(("{0:d} is not a multiple " +
"of {1:d}!").format(d[k], d0[k]))
elif d[k] == d0[k]:
pass
else:
if d0[k] % d[k] != 0:
raise ValueError(("{0:d} is not a multiple " +
"of {1:d}!").format(d0[k], d[k]))
xx = x.copy()
new_shape = list(d0)
for k in range(len(d0)):
new_shape[k] = d[k]
r = zeros(new_shape, dtype=xx.dtype)
sliceobj0 = [slice(None)]*len(d0)
sliceobj1 = [slice(None)]*len(d0)
sliceobj = [slice(None)]*len(d)
f = d0[k]/d[k]
if d[k] > d0[k]:
for i in range(d[k]):
p = f*i
fp = int(floor(p))
sliceobj0[k] = slice(fp, fp + 1)
sliceobj[k] = slice(i, i + 1)
if sample:
r[sliceobj] = xx[sliceobj0]
else:
if p < d0[k] - 1:
sliceobj1[k] = slice(fp + 1, fp + 2)
rshape = r[sliceobj].shape
r[sliceobj] = (xx[sliceobj0].reshape(rshape) +
(p - fp)*(xx[sliceobj1] -
xx[sliceobj0]).reshape(rshape)
)
else:
r[sliceobj] = xx[sliceobj0]
elif d[k] == d0[k]:
for i in range(d[k]):
sliceobj0[k] = slice(i, i + 1)
sliceobj[k] = slice(i, i + 1)
r[sliceobj] = xx[sliceobj0]
else:
for i in range(d[k]):
sliceobj[k] = slice(i, i + 1)
if sample:
fp = int(floor(f*i))
sliceobj0[k] = slice(fp, fp + 1)
r[sliceobj] = xx[sliceobj0]
else:
sliceobj0[k] = slice(int(f*i), int(f*(i+1)))
rshape = r[sliceobj].shape
r[sliceobj] = xx[sliceobj0].sum(k).reshape(rshape)/f
xx = r
return r
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