从文本文件中读取列表并交换项目

Question

I have a list in a text file in this format. The list has 1000's of entries like this and this is a small sample.

myitems =[
      ['some text, A', '12345'],
      ['place name 1', 'AAA'],
      ['some text, A', '12345'],
      ['some text', '12345'],
      ['some text CC', 'wwww'],
      ['new text', '12345'],
      ['other text, A', '12345'],
    ]

How do i read the list from the text file and get an output like this.

newItems = [
  ['12345', 'some text, A'],
  ['AAA', 'place name 1'],
  ['12345', 'some text, A'],
  ['12345', 'some text'],
  ['wwww', 'some text CC'],
  ['12345', 'new text'],
  ['12345', 'other text, A'],
]

I am able to read from the file and manipulate it as a string but how do i get it as a list. Breaking at the comma isn't an option since individual list items might have a comma.

Answer 1

最简单的是列表理解：

new_items = [i[::-1] for i in myitems]

Answer 2

 newItems = [[b, a] for a, b in myitems]

Answer 3

import sys

# Reading your file (the path has been passed in argument) and storing each lines in the array called "input"
input = []
with open(sys.argv[1], 'r') as all_lines:
    for line in all_lines:
        if line:
            input.append(line)

# Creating your array "newItems"
for j in input: 
    print j

newItems = []
if len(input)>2:
    for i in range(1, len(input)-1):
        # Getting content inside brackets. Ex: {{ 'some text, A', '12345' }}
        my_str = input[i].split("[")[1].split("]")[0]
        my_elements = my_str.split("'")

        # Appending elements
        newItems.append([my_elements[1], my_elements[3]])

print  newItems

Answer 4

if it really looks like that then

 with open(my_file) as f:
   exec(f.read()) #read in the text and evaluate it in python creating myitems variable
   my_list = [reversed(l) for l in myitems]

exec is very dangerous and should most likely not be used ... but this should work

better solution

 #name yourfile with the myitems = [...] to items.py
 import items
 new_items = [reversed(l) for l in items.myitems]

Answer 5

import re

f = open('myfile.txt', 'r')
newItems = []
for line in f:
    foo = re.search("\'(.*)\'.*\'(.*)\'", line) #we assume the values are 
                                                #in single quotes
    if foo is not None:
        a, b = foo.groups()
        newItems.append([b, a])

Answer 6

To read the file, use CSV since you state 'the individual items might have commas'

Example:

if your file actually looks like this:

'some text, A','12345'
'place name 1','AAA'
'some text, A','12345' 
'some text','12345'
'some text CC','wwww' 
'new text','12345'
'other text, A','12345'

Then this code reads the csv file and reverses the fields:

import csv

with open('test.csv','rb') as csvIN:
    for row in csv.reader(csvIN, delimiter=',',quotechar="'"):
        print row
        row=row[::-1]
        print '==>',row,'\n'

Prints:

['some text, A', '12345']
==> ['12345', 'some text, A'] 

['place name 1', 'AAA']
==> ['AAA', 'place name 1'] 

['some text, A', '12345 ']
==> ['12345 ', 'some text, A'] 

['some text', '12345']
==> ['12345', 'some text'] 

['some text CC', 'wwww ']
==> ['wwww ', 'some text CC'] 

['new text', '12345']
==> ['12345', 'new text'] 

['other text, A', '12345']
==> ['12345', 'other text, A']