python等价于Matlab展平答案

【问题标题】：python equivalence to Matlab flatteningpython等价于Matlab展平
【发布时间】：2021-11-25 07:54:04
【问题描述】：

我正在尝试将此代码从 matlab 转换为 python：

Matlab

 lP =lP(:)/length(lP(:));
  lM=lM(:)/length(lP(:));

我的尝试：

lP=ravel(lP) / length(ravel(lP))
lM=ravel(lM) / length(ravel(lP))

不幸的是，扁平化过程似乎以不兼容的方式结束： Matlab 以： lP =

                     0
                     0
      282.158675652645
      245.206579787908
      180.857334994335
      145.295985608783
      98.6111323759356
      78.6541285064253
                     0
                     0
      235.988440426672
      252.705377114354
      149.700677619887
      149.441877249856
      94.6327116403152
      84.5507642298126
       201.33034579544
        168.5504445176
      112.020019512079
      100.029337003081
      81.9696997469859
      77.2791884039185
      53.8857894853351
      47.1052112310254
      201.005392514542
      170.334647413678
      102.794197425736
      117.624998880039
      63.5474961850914
      85.6855606877716
      40.2032122529948
      55.9023649432995
      113.662165613052
      105.200545764806
       66.249378944203
      60.9266562306452
      46.1411501598512
      44.4884016760164
      31.2403038422145
      31.8768645697115
      96.6943687173171
      94.3667944720464
      63.9090790984522
      63.4837480098802
       43.801313157197
      47.5765809365761
      27.4423759004399
      31.6859217744796
      74.7724121990454
       66.780700287442
      35.6152335123858
      37.2132749966295
      27.2233609912034
      28.2363756837094
      18.7629642336031
       19.217036195859
      55.1857268319806
      49.2057110093965
      35.3827383680906
      33.9961168439708
      26.0418645945658
      26.2135571149649
      17.8586181284183
      18.6567862728906

而 python 以 lP= 结尾：

    [[  0.        ],
   [  0.        ],
   [282.15867565],
   [245.20657979],
   [ 35.61523351],
   [ 37.213275  ],
   [ 74.7724122 ],
   [ 66.78070029],
   [  0.        ],
   [  0.        ],
   [235.98844043],
   [252.70537711],
   [ 35.38273837],
   [ 33.99611684],
   [ 55.18572683],
   [ 49.20571101],
   [201.3303458 ],
   [168.55044452],
   [112.02001951],
   [100.029337  ],
   [ 66.24937894],
   [ 60.92665623],
   [113.66216561],
   [105.20054576],
   [201.00539251],
   [170.33464741],
   [102.79419743],
   [117.62499888],
   [ 63.9090791 ],
   [ 63.48374801],
   [ 96.69436872],
   [ 94.36679447],
   [ 53.88578949],
   [ 47.10521123],
   [ 81.96969975],
   [ 77.2791884 ],
   [ 46.14115016],
   [ 44.48840168],
   [ 31.24030384],
   [ 31.87686457],
   [ 40.20321225],
   [ 55.90236494],
   [ 63.54749619],
   [ 85.68556069],
   [ 43.80131316],
   [ 47.57658094],
   [ 27.4423759 ],
   [ 31.68592177],
   [ 98.61113238],
   [ 78.65412851],
   [180.85733499],
   [145.29598561],
   [ 27.22336099],
   [ 28.23637568],
   [ 18.76296423],
   [ 19.2170362 ],
   [ 94.63271164],
   [ 84.55076423],
   [149.70067762],
   [149.44187725],
   [ 26.04186459],
   [ 26.21355711],
   [ 17.85861813],
   [ 18.65678627]]

似乎python对块展平做出了不同的选择，有人知道我怎样才能用python达到与matlab相同的结果吗？

【问题讨论】：

lP 是什么？ lM 是什么？ ravel() 是什么？
对我来说，在 Matlab 中它看起来不像 flattening，而是像 normalization。也许Matlab 也显示 2D 数组，但方式略有不同，您只需在 Python 中手动格式化结果以以相同方式显示 2D 数组。它可能需要使用for-loop 并单独显示每个元素 - 比如for row in IP: print(row[0])

标签： python arrays matlab matrix flatten

【解决方案1】：

最可能的问题是数组排序。 Numpy 默认使用行优先（C 风格）排序，而 MATLAB 仅支持列优先（Fortran 风格）。所以这应该有效：

lP=ravel(lP, 'F') / length(ravel(lP))
lM=ravel(lM, 'F') / length(ravel(lP))

但是，numpy 直接将很多东西附加到数组中，所以这种语法更简洁：

lP = lP.ravel('F') / length(lP.ravel())
lM = lM.ravel('F') / length(lP.ravel())

而扁平化数组的长度就是它的.size，所以可以进一步简化为：

lP = lP.ravel('F') / lP.size
lM = lM.ravel('F') / lP.size

【讨论】：