python - 将文本文件中的第一列数据转换为python中的列表

Question

我想将文本文件中的第一列数据转换为python中的列表

data = open ('data.txt', 'r')
data.read()

提供

'12 45\n13 46\n14 47\n15 48\n16 49\n17 50\n18 51'

任何帮助，请。

Answer 1

你可以str.split在这里使用和list comprehension：

with open('data.txt') as f:
   lis = [int(line.split()[0]) for line in f]
>>> lis
[12, 13, 14, 15, 16, 17, 18]

如果数字是字符串：

>>> with open('abc') as f:
       lis = [line.split()[0] for line in f]
>>> lis
['12', '13', '14', '15', '16', '17', '18']

简化版：

>>> with open('abc') as f:     #Always use with statement for handling files
...     lis = []
...     for line in f:         # for loop on file object returns one line at a time
...         spl = line.split() # split the line at whitespaces, str.split returns a list
...         lis.append(spl[0]) # append the first item to the output list, use int() get an integer
...     print lis    
...     
['12', '13', '14', '15', '16', '17', '18']

帮助和示例str.split：

>>> strs = "a b c d ef gh i"
>>> strs.split() 
['a', 'b', 'c', 'd', 'ef', 'gh', 'i']
>>> print str.split.__doc__
S.split([sep [,maxsplit]]) -> list of strings

Return a list of the words in the string S, using sep as the
delimiter string.  If maxsplit is given, at most maxsplit
splits are done. If sep is not specified or is None, any
whitespace string is a separator and empty strings are removed
from the result.

Answer 2

import csv
with open ('data.txt', 'rb') as f:
    print [row[0] for row in csv.reader(f, delimiter=' ')]

---

['12', '13', '14', '15', '16', '17', '18']