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[英]ValueError: operands could not be broadcast together with shapes (120,) (6,)
[英]MATLAB TO PYTHON conversion [ValueError: operands could not be broadcast together with shapes (120,) (6,) ]
所以這是我的 python 代碼
import numpy as np
n = 3
T = 100
ts = .2*(100/(2*n-3))
tv = .6*((100-((2*n-3)*ts))/(2*(n-1)))
m1 = np.arange(0,tv,0.1);
x1 = 0.5*(1-(np.cos(np.pi*(m1/tv))))
xa = x1;
#%travelling from right to left
xd = np.flip(xa)
xw = []
for i in range(1,n-1):
if i==1:
pass
else:
xd = xd-1
#%standing at one point
for f in np.arange(1,ts):
mini = np.amin(xd)
xw.append(mini)
if i==1:
xm=np.array([xd,xw])
else:
xm = np.array([xm,xd,xw])
xm = abs(np.amin(xm)) + xm
當我運行它時,會出現一大堆錯誤塊。 我知道 arrays 必須具有相同的等級才能執行數學運算,但我不知道如何在此處執行此操作。
這是我運行代碼時出現的錯誤塊
---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
<ipython-input-7-64722470b31e> in <module>
32 xm = np.array([xm,xd,xw])
33
---> 34 xm = abs(np.amin(xm)) + xm
35
36
<__array_function__ internals> in amin(*args, **kwargs)
~\anaconda3\lib\site-packages\numpy\core\fromnumeric.py in amin(a, axis, out, keepdims, initial, where)
2856 6
2857 """
-> 2858 return _wrapreduction(a, np.minimum, 'min', axis, None, out,
2859 keepdims=keepdims, initial=initial, where=where)
2860
~\anaconda3\lib\site-packages\numpy\core\fromnumeric.py in _wrapreduction(obj, ufunc, method, axis, dtype, out, **kwargs)
85 return reduction(axis=axis, out=out, **passkwargs)
86
---> 87 return ufunc.reduce(obj, axis, dtype, out, **passkwargs)
88
89
ValueError: operands could not be broadcast together with shapes (120,) (6,)
這是 Matlab 代碼
xd = flip(xa);
for i= 1:n-1
if i==1
else
xd = xd-1;
end%standing at one point
for f = 1:ts
xw(f) = min(xd);
end
if i==1
xm=[xd,xw];
else
xm = [xm,xd,xw];
end
end
xm = abs(min(xm))+xm;
disp(xm);
這是我從運行 MATLAB 代碼得到的 output,這也是我期望從我的 python 代碼得到的 output。
>>
Columns 1 through 13
2.0000 1.9998 1.9993 1.9985 1.9973 1.9957 1.9938 1.9916 1.9891 1.9862 1.9830 1.9794 1.9755
Columns 14 through 26
1.9713 1.9668 1.9619 1.9568 1.9513 1.9455 1.9394 1.9330 1.9263 1.9193 1.9121 1.9045 1.8967
Columns 27 through 39
1.8886 1.8802 1.8716 1.8627 1.8536 1.8442 1.8346 1.8247 1.8147 1.8044 1.7939 1.7832 1.7723
Columns 40 through 52
1.7612 1.7500 1.7386 1.7270 1.7153 1.7034 1.6913 1.6792 1.6669 1.6545 1.6420 1.6294 1.6167
Columns 53 through 65
1.6040 1.5911 1.5782 1.5653 1.5523 1.5392 1.5262 1.5131 1.5000 1.4869 1.4738 1.4608 1.4477
Columns 66 through 78
1.4347 1.4218 1.4089 1.3960 1.3833 1.3706 1.3580 1.3455 1.3331 1.3208 1.3087 1.2966 1.2847
Columns 79 through 91
1.2730 1.2614 1.2500 1.2388 1.2277 1.2168 1.2061 1.1956 1.1853 1.1753 1.1654 1.1558 1.1464
Columns 92 through 104
1.1373 1.1284 1.1198 1.1114 1.1033 1.0955 1.0879 1.0807 1.0737 1.0670 1.0606 1.0545 1.0487
Columns 105 through 117
1.0432 1.0381 1.0332 1.0287 1.0245 1.0206 1.0170 1.0138 1.0109 1.0084 1.0062 1.0043 1.0027
Columns 118 through 130
1.0015 1.0007 1.0002 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 0.9998 0.9993
Columns 131 through 143
0.9985 0.9973 0.9957 0.9938 0.9916 0.9891 0.9862 0.9830 0.9794 0.9755 0.9713 0.9668 0.9619
Columns 144 through 156
0.9568 0.9513 0.9455 0.9394 0.9330 0.9263 0.9193 0.9121 0.9045 0.8967 0.8886 0.8802 0.8716
Columns 157 through 169
0.8627 0.8536 0.8442 0.8346 0.8247 0.8147 0.8044 0.7939 0.7832 0.7723 0.7612 0.7500 0.7386
Columns 170 through 182
0.7270 0.7153 0.7034 0.6913 0.6792 0.6669 0.6545 0.6420 0.6294 0.6167 0.6040 0.5911 0.5782
Columns 183 through 195
0.5653 0.5523 0.5392 0.5262 0.5131 0.5000 0.4869 0.4738 0.4608 0.4477 0.4347 0.4218 0.4089
Columns 196 through 208
0.3960 0.3833 0.3706 0.3580 0.3455 0.3331 0.3208 0.3087 0.2966 0.2847 0.2730 0.2614 0.2500
Columns 209 through 221
0.2388 0.2277 0.2168 0.2061 0.1956 0.1853 0.1753 0.1654 0.1558 0.1464 0.1373 0.1284 0.1198
Columns 222 through 234
0.1114 0.1033 0.0955 0.0879 0.0807 0.0737 0.0670 0.0606 0.0545 0.0487 0.0432 0.0381 0.0332
Columns 235 through 247
0.0287 0.0245 0.0206 0.0170 0.0138 0.0109 0.0084 0.0062 0.0043 0.0027 0.0015 0.0007 0.0002
Columns 248 through 254
0 0 0 0 0 0 0
>>
當你運行這段代碼時,你有沒有 git 參差不齊的ragged array
警告? 如果是這樣,你為什么忽略它? 還是您正在運行這么舊的numpy
以致於它沒有發出警告?
<ipython-input-1-7dab9a6384c7>:24: VisibleDeprecationWarning: Creating an ndarray from ragged nested sequences (which is a list-or-tuple of lists-or-tuples-or ndarrays with different lengths or shapes) is deprecated. If you meant to do this, you must specify 'dtype=object' when creating the ndarray.
xm=np.array([xd,xw])
In [2]: xm
Out[2]:
array([array([9.99828662e-01, 9.99314767e-01, 9.98458667e-01, 9.97260948e-01,
9.95722431e-01, 9.93844170e-01, 9.91627454e-01, 9.89073800e-01,
...
1.54133313e-03, 6.85232623e-04, 1.71337512e-04, 0.00000000e+00]),
list([0.0, 0.0, 0.0, 0.0, 0.0, 0.0])], dtype=object)
In [3]: xm.shape
Out[3]: (2,)
In [4]: xm.dtype
Out[4]: dtype('O')
In [5]: xm[0].shape
Out[5]: (120,)
In [7]: len(xm[1])
Out[7]: 6
xm
是 object dtype,包含一個數組和一個列表。 它們的長度與錯誤中所述的長度相匹配: shapes (120,) (6,)
您不能在這樣的數組上執行np.min
。
我不會嘗試理清你的xm
構造函數的邏輯,但我看到你使用xw
作為列表和列表 append,但xm
作為數組和np.array([...])
在循環中生成新值. 在循環中重復np.array
不是一個好主意; 它很慢並且容易出錯。 這同樣適用於在循環中使用np.concatenate
(或其衍生物之一)。 如果您要反復工作,請堅持使用列表,並在需要時撥打 arrays,最后打一個電話。
當我使用 MATLAB 時,大約是 3.9 版,我們試圖避免循環,因為它們很慢。 從那時起 MATLAB 添加jit
編譯,因此沒有太多時間損失。 numpy
還是最好避免循環,或者用numba
來編譯。
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