如何在命令行中将参数传递给文件并使用python更改文件内的字符串？

Question

我有一个文件 requirements.txt 文件。以下文本如下。如何更改 django 和 flask 的值并通过作为命令行参数传递来更新文件

requirement.txt

 numpy=1.14
 pandas=1.4
 django=1.6
 flask=1.4

我的 python file.py 在下面

 import sys
 import re
 program_name = sys.argv[0]
 arguments = sys.argv[1:]
 print (arguments[0])
 print (arguments[1])
 with open('requirement.txt ', 'r') as fr:
     data = fr.readlines()
     with open('requirement.txt ', 'a') as fw:
     fw.write(....)

python file.py django=2.1 flask=2.0

requirements.txt 的输出

 numpy=1.14
 pandas=1.4
 django=2.1 
 flask=2.0

Answer 1

import re
import sys

arguments = dict(i.split("=") for i in sys.argv[1:])   #CMD line Arguments.
with open('requirement.txt', 'r') as fr:         #Read content
    data = fr.read()

for k, v in arguments.items():
    data = re.sub(r"{}=(.*)".format(k), "{}={}".format(k,v), data)   #Update content

with open(filename, 'w') as fr:              #Write back data. 
    fr.write(data)

Answer 2

我想你可能想看看 argparse： https://docs.python.org/2/library/argparse.html

否则，你可以这样做：

import sys

requirements = {}

# Save a list of requirements
with open('requirement.txt', 'r') as file:
  for line in file:
    line = line.strip("\n").split("=")
    requirements[line[0]] = line[1]

# Change requirements values
for command in sys.argv[1:]:
  command = command.split("=")
  requirements[command[0]] = command[1]

# Write requirements back to file
with open('requirement.txt', 'w') as file:
  for r, v in requirements.items():
    line = "{}={}\n".format(r, v)
    file.write(line)

Answer 3

使用方便的fileintput 模块 - 在一个 中编辑：

import sys
import fileinput

program_name = sys.argv[0]
args = sys.argv[1:]

if not args:    # ensuring replacement items were passed
    sys.exit('No items to replace')

args_dict = dict(arg.split('=') for arg in args)
keys_tuple = tuple(args_dict.keys())

for line in fileinput.input(files='requirements.txt', inplace=True):
    if line.startswith(keys_tuple):
        name, version = line.split('=')
        line = line.replace(version, args_dict[name])
    print(line.strip())

最终的requirements.txt文件内容：

numpy=1.14
pandas=1.4
django=2.1
flask=2.0

Answer 4

使用“a”表示您将有两个相同类型的需求，如下所示：

numpy=1.14
pandas=1.4
django=1.6
flask=1.4
django=2.1 
flask=2.0

相反，您应该使用更新的需求列表覆盖文件。

首先，加载数据并将其放入字典中：

fr=open('requirement.txt ', 'r')
L=fr.read().split("\n") #Better than .readlines(), since it removes '\n'
fr.close() #Very important, since you're going to write back into it.
D=dict()
for e in L:
    E=e.split("=")
    if len(E)<2:
        continue
    D[E[0]]=E[1]

然后，将参数应用于字典：

D[arguments[0]]=arguments[1]

最后，将字典数据放回字符串并覆盖文件：

result="\n".join([e+"="+D[e] for e in D])
fw=open('requirement.txt ', 'a')
fw.write(result)
fw.close()

应该会得到想要的结果。

此外，如果您希望保留它，您应该跟踪列表中键的顺序。