[英]Python wrong behavior for the SUM OF 2D numpy.array
所以,我有一个数字列表
weird_list = [800153196,
946067665,
827629917,
868941741,
875745873,
926109150,
1353347195,
1003235074,
1053666891,
1442194993,
1924716858,
1060724069,
1182240731,
1646547575,
1215762661,
1520107722,
1512568609,
1534064291,
1549459216,
1773697582,
1853820087,
1696910852,
1563415785,
1692314635,
1627783113]
我的目标是获得此列表中每对总和的 2d np.array 。
例子:
weird_list = [1, 2, 3]
resulting_array = [[0, 1, 2],
[1, 2, 3],
[2, 3, 4]]
我写了这个 function,它适用于较小的数字,但不是必需的,因为我在 arrays 上用更大的数字进行了测试。 这个数组的问题是我以某种方式获得了负数。
def array_sum(i_list):
i_array = np.array(i_list) # converts list to np.array
i_array_rs1 = i_array.reshape(1, -1)
i_array_rs2 = i_array.reshape(-1, 1)
i_array_rs_SUM = i_array_rs1 + i_array_rs2
print(i_array_rs_SUM) # prints the sum of reshaped arrays, which doesn't work for my input list
我还尝试了一些带有较小/较大数字列表的示例
low_list = [0, 1, 2, 3]
ex_list = []
weird_list_div_10 = []
weird_list_mult_10 = []
for i in range(len(weird_list)):
ex_list.append(i)
weird_list_div_10.append(weird_list[i] // 10)
weird_list_mult_10.append(weird_list[i] * 10)
完整代码来源: https://pastebin.com/pKpgEtUm
import numpy as np
weird_list = [ 926109150, 1353347195, 1003235074 ]
arr = np.array( weird_list, dtype = np.int32 ) # int32 forced here
arr.reshape( 1, -1 ) + arr.reshape( -1, 1 )
# Out[12]: # int32 leads to some negative answers.
# array([[ 1852218300, -2015510951, 1929344224],
# [-2015510951, -1588272906, -1938385027],
# [ 1929344224, -1938385027, 2006470148]], dtype=int32)
2**31-1
# Out[14]: 2147483647 # Any number greater than this in int32 will be truncated to it's
# 32 lowest bits. if bit 31 ( counting bits 0 to 31 ) is 1 it's treated as a negative number.
arr = np.array( weird_list, dtype = np.int64 ) # int64 forced.
arr.reshape( 1, -1 ) + arr.reshape( -1, 1 )
# Out[16]: # int64 doesn't overflow therefore all results are positive with these values
# array([[1852218300, 2279456345, 1929344224],
# [2279456345, 2706694390, 2356582269],
# [1929344224, 2356582269, 2006470148]])
使用原始怪异列表中的值 uint32 可以。 最高位不表示无符号整数的符号。
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