使用Python打印出像表一样的2D列表 [英] Printing out a 2D list like a table with Python

问题描述

我正在尝试打印出像桌子一样的2D列表，并且在这里找到了一段代码:漂亮的2D Python列表

但是我不知道它是如何工作的，有人可以向我解释吗?

  s = [[行中e的str(e)]矩阵中的行]lens = [max(map(len, col)) for col in zip(*s)]fmt ='\ t'.join('{{:{}}}'.. format(x)for x in lens)table = [fmt.format(* row)for s in row]打印 '\n'.join(table) 

解决方案

正如其他人所评论的，这里有很多概念(太多的问题无法在一个答案中处理).但是，为了进行进一步的研究(使用(小的)示例2D列表依次尝试每个语句)，请按以下步骤进行分解:

将数据转换为字符串列表(使用 list理解):

  s = [[行中e的str(e)]矩阵中的行] 

获取每列中最大字符数的列表，以便我们了解如何格式化列:

lens = [max(map(len, col)) for col in zip(*s)] 

(这一点比较复杂: zip()在这里使我们能够遍历 s 的列，并将它们分别传递给 len()方法来查找其长度(这是通过 map()实现的；然后使用内置的 max()找到每一列的最大长度.)

将相应的Python格式字符串设置为制表符分隔的条目:

  fmt ='\ t'.join('{{:{}}}'.format(x)for lens in x) 

fmt 现在是每一行的格式说明符，例如'{:4} \ t {:6} \ t {:6}'，用于宽度为4,6,6的三列(NB仅适用于Python 2.7+，因为字段尚未被使用编号)

将表设置为字符串格式的行列表(使用其他列表理解):

  table = [s中的行的fmt.format(* row)] 

用一个字符串将整个行连接在一起，行之间用换行符分隔:

 打印'\ n'.join(表) 

join()提取一个字符串列表，并生成一个字符串，这些字符串均通过选定的定界符(此处为 \ n ，换行符)连接在一起./p>

I'm trying to print out a 2D list like a table, and I found a piece of code here: Pretty print 2D Python list

But I couldn't understand how it really works, can anyone please explain to me?

s = [[str(e) for e in row] for row in matrix]
lens = [max(map(len, col)) for col in zip(*s)]
fmt = '\t'.join('{{:{}}}'.format(x) for x in lens)
table = [fmt.format(*row) for row in s]
print '\n'.join(table)

解决方案

As others have commented, there are a lot of concepts going on here (too many to be manageable in a single answer). But for your further study (try out each statement in turn with a (small) example 2D list), here's how it breaks down:

Turn the data into a list of lists of strings (uses list comprehension):

s = [[str(e) for e in row] for row in matrix]

Get a list of the maximum number of characters in each column so we know how to format the columns:

lens = [max(map(len, col)) for col in zip(*s)]

(This one is more complex: zip() here enables us to iterate over the columns of s, passing each to the len() method to find its length (this is achieved with map()); then find the maximum length of each column with the max() builtin.)

Set up the corresponding Python format strings as tab-separated entries:

fmt = '\t'.join('{{:{}}}'.format(x) for x in lens)

fmt is now the format specifier for every row, e.g. '{:4}\t{:6}\t{:6}' for three columns with widths 4,6,6 (NB only works on Python 2.7+ because the fields haven't been numbered)

Set up the table as a list of rows in their string format (use another list comprehension):

table = [fmt.format(*row) for row in s]

Join the whole lot together in a single string, with rows separated by newlines:

print '\n'.join(table)

join() takes a list of strings and produces one string with them all joined together by the chosen delimiter (here, \n, the newline character).

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