# python中的numpy数组的随机大小分块

``````a = np.arange(1, 100)

def chunk(xs, n): # to chunk the array xs in n parts
ys = list(xs)
random.shuffle(ys)
size = len(ys) // n
leftovers= ys[size*n:]
for c, xtra in enumerate(leftovers):
yield ys[c*size:(c+1)*size] + [ xtra ]
for c in xrange(c+1,n):
yield ys[c*size:(c+1)*size]
``````

``````from itertools import chain
import numpy as np

a = np.arange(1, 100)
def chunk(xs, nlow, nhigh, shuffle=True):
xs = np.asarray(xs)
if shuffle:
# shuffle, if you want
xs = xs.copy()
np.random.shuffle(xs)

# get at least enough random chunk sizes in the specified range, ie nlow <= n <= nhigh
ns = np.random.randint(nlow, nhigh+1, size=xs.size//nlow)
# add up the chunk sizes to get the indices at which we'll slice up the input array
# truncate ixs so that its contents are all valid indices with respect to xs
ixs = ixs[:np.searchsorted(ixs, xs.size)]

# yield slices from the input array
for start,end in zip(chain([None], ixs), chain(ixs, [None])):
yield xs[start:end]

list(chunk(a, 5, 10))
``````

``````[array([67, 79, 17, 62, 12, 37, 70, 24]),
array([98, 48, 88, 59, 47]),
array([52, 60, 89, 23, 43, 44]),
array([ 7, 27, 33, 74, 49,  2]),
array([ 6, 51, 40, 13, 56, 45]),
array([31,  3, 55, 10, 11, 46,  9, 42, 34]),
array([53, 22, 95, 41, 19, 32,  4, 69, 86]),
array([93, 68, 57, 65, 92, 76, 28, 63, 64, 58]),
array([91, 66, 18, 99, 21]),
array([36, 83, 15, 78,  1, 81, 97, 84]),
array([61, 71, 25, 94, 87, 20, 85, 38]),
array([ 8, 96, 75, 30, 77, 14, 72, 29]),
array([35, 90, 82, 73, 39,  5, 26, 50, 16]),
array([80, 54])]
``````

# 编辑

``````def getIxs(xsize, nlow, nhigh):
# get at least enough random chunk sizes in the specified range, ie nlow <= n <= nhigh
ns = np.random.randint(nlow, nhigh+1, size=xsize//nlow)

# add up the chunk sizes to get the indices at which we'll slice up the input array

# truncate ixs so that its contents are all valid indices with respect to xs
ixs = ixs[:np.searchsorted(ixs, xsize)]

return ixs

def chunk(xs, nlow, nhigh):
xs = np.asarray(xs)

ixs = getIxs(xs.size, nlow, nhigh)

# rerun getIxs until the size of the final chunk is large enough
while (xs.size - ixs[-1]) < nlow:
ixs = getIxs(xs.size, nlow, nhigh)

# yield slices from the input array
for start,end in zip(chain([None], ixs), chain(ixs, [None])):
yield xs[start:end]
``````

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