Python：将大量2D列表追加到一个2D列表

问题描述

为简单起见，我将仅使用两个列表。因此，我有以下2D列表：

> > a = [[1,2,3],> >      [1,3]]   
> > b = [[4,5,6],> >      [4,6]]

如果我追加列表a和b，则希望获得以下内容：

masterlist = [[1,4],[2,5],[3,[1,6]]

以下代码是我尝试过的：

filenames = [a,b]           #For the example,since I will have multiple arrays 
masterlist = [] 
counter = 0 
for file in filenames:
    if counter == 0:        #This if is to try to create lists within the list
        for row in file:    #This loops is to iterate throughout the whole list
                for col in row:
                    c = [masterlist.append([col])]
        [masterlist.append(c) for row,col in zip(masterlist,c)]
        counter = 1
    else:                   #This else is to append each element to their respective position
        for row in file:
                for col in row:
                    c = [masterlist.append(col)]
        [masterlist.append([c]) for row,c)]

打印主列表时的输出如下：

[[1],[2],[3],[1],[None],4,6,[[None]]]

我不确定[无]的来源。正如我们所看到的，“ 4,6 ...”没有分别附加到列表“ [1]，[2]，[3] ...”。

解决方法

您可以遍历列表中的项目，然后将其添加到您的主列表中：

a = [[1,2,3],[1,3]]   
b = [[4,5,6],[4,6]]

masterlist = []

for aa,bb in zip(a,b):                 # loop over lists
    for itema,itemb in zip(aa,bb):    # loop over items in list
        masterlist = masterlist + [[itema,itemb]]

输出：

[[1,4],[2,5],[3,6]]

如果您使用numpy，这真的很简单

import numpy as np
a = np.array([[1,3]])
    
b = np.array([[4,6]])

fl = np.vstack(np.dstack((a,b)))

输出

array([[1,6]])

list loops python