Question

我想选择一个特定的角色。假设文件old.txt包含xxXXyyaasdyyYY。在该文件中，只应保留X和Y并将其写入new.txt。下面的代码出了什么问题？

in_file = open("old.txt", "r")
out_file = open("new.txt","w")
for line in in_file:
    out_file.write(line.upper())
in_file.close()
out_file.close()

Answer 1

in_file = open("old.txt", "r")
out_file = open("new.txt","w")
for line in in_file:
  for letter in line:
    if (letter == 'X') | (letter == 'Y'):
        out_file.write(letter.upper())
in_file.close()
out_file.close()

Answer 2

您可以使用白名单set和上下文管理器（使用with关键字）来使这更加惯用。

whitelist = {"X", "Y"}

with open('old.txt') as in_file,
        open('new.txt', 'w') as out_file:
    for line in in_file:
        for letter in line:
            if letter in whitelist:
                out_file.write(letter)  # no need to uppercase here
# no need to close either, since we're using the with statement

Answer 3

由于您想要选择字符，您可以一次阅读一个字符。

from collections import defaultdict

specific_characters = ['X', 'Y']
counter_dict = defaultdict(lambda: 0)

with open("old.txt", "r") as in_file, open("new.txt","a") as out_file:
  while True:
    c = in_file.read(1)
    if not c:
      break
    if c in specific_characters:
      out_file.write(c)
      counter_dict[c] += 1

# printing just X and Y for your specific case. 
# the counter will have count of any characters from the specific_characters list.

print "Count of X: ", counter_dict['X']
print "Count of Y: ", counter_dict['Y']

仅保留一个文本文件中的特定字符，并将其写入新的文本文件中

3 个答案: