分割数组时减少内存使用的最佳做法

Question

I have an array that I want to split up in two halves. Because of symmetry I am only interested in keeping the left half of the array.

I can split the array in half by saying:

[a,b] = numpy.split(c,2)

where c is also an array.

Is there a way to only return the 'a' array, or alternatively removing the 'b' array from memory immediately after splitting the array?

Answer 1

You can copy the first half with

a = x[len(x)//2:].copy()

this would need to allocate the copy and move the content (thus temporarily needing 1.5 times the memory)

Otherwise you can just say

a = x[len(x)//2:]

to get a reference to the first half, but the other part will not be removed from memory

Answer 2

Simply you can use delete function for this aim! this is an example :

array=np.array([1,2,3,4])
x=len(array)/2
first_h=np.delete(array,array[x-1:])         #second half

Demo:

>>>print first_h
>>>[1,2]

Answer 3

I'm not sure, but I think this might be best because it relies on list 's implementation ( docs ) and I'm confident it was done right:

>>> r = range(10)
>>> r
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> del r[5:]
>>> r
[0, 1, 2, 3, 4]

See also del statement for lists .