與numpy.array返回數組以零

除以整數我似乎有一些問題，將一個整數與numpy.array .. 這樣做似乎回到零的陣列，而不是小數值..與numpy.array返回數組以零

例如：

>>> import numpy as np 
>>> length = 257 
>>> length = 256 
>>> x = np.array(range(0,length) 
...) 
>>> x 
array([ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 
     13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 
     26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 
     39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 
     52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 
     65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 
     78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 
     91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 
     104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 
     117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 
     130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 
     143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 
     156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 
     169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 
     182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 
     195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 
     208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 
     221, 222, 223, 224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 
     234, 235, 236, 237, 238, 239, 240, 241, 242, 243, 244, 245, 246, 
     247, 248, 249, 250, 251, 252, 253, 254, 255]) 
>>> x*1/length 
array([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
     0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
     0, 0, 0]) 
>>>

爲什麼它返回零？

來源

2017-01-13 I am not Fat

無法重現此，我得到的所有彩車 – EdChum

因爲你面對的所有整數並且是'Python2.x'重複性。對於浮點結果，請使用：from __future__ import division。 – Divakar

這是因爲它正在進行整數除法。試試這個

x*1/256.0

來源

2017-01-13 12:11:51 gipsy

結束了只是把它轉換爲浮動..一個巴姆..適當的分工:) –

因爲陣列由出整數，並且在python-2.x/被定義爲整數除法其向下舍入的結果，所以99/100被認爲是0。

你可以先轉換爲float：

x.astype(float)*1/length

浮子浮點和這樣的數據結構 - 把它大膽 - 支持數字與十進制點。

來源

2017-01-13 12:08:31

與numpy.array返回數組以零

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