如何在Python中合并多个文件

Question

非常简单的问题！我想合并多个JSON文件和

看看这个：

f1data = f2data = f3data = f4data = f5data = f6data = "" 
 
with open('1.json') as f1: 
  f1data = f1.read() 
with open('2.json') as f2: 
  f2data = f2.read() 
with open('3.json') as f3: 
  f3data = f3.read() 
with open('4.json') as f4: 
  f4data = f4.read() 
with open('5.json') as f5: 
  f5data = f5.read() 
with open('6.json') as f6: 
  f6data = f6.read() 
 
f1data += "\n"
f1data += f2data += f3data += f4data += f5data += f6data 
with open ('merged.json', 'a') as f3: 
  f3.write(f1data)
  

输出应该是这样的：

[
    {
        "id": "1",
        "name": "John",
    },

    {
        "id": "2",
        "name": "Tom",
    }
]

问题是Visual Code Studio在下面出现了一条红线： f1data+=f2data+=f3data+=f4data+=f5data+=f6data

我不知道为什么！代码无法运行！没有错误，所以我可以排除故障。有什么建议吗

Answer 1

“合并”文件的输出不会像您指定的那样格式化，但这表明了我个人将使用的方法：-

import json
alist = []
with open('/Users/andy/merged.json', 'w') as outfile:
    for k in range(6):
        with open(f'/Users/andy/{k+1}.json') as infile:
            alist.append(json.load(infile))
    outfile.write(str(alist))

Answer 2

此代码中有几点需要改进：

你应该以更“程序化”的方式考虑：

如果声明一个包含要访问的json文件名称的列表，如下所示：

files_names = ["1","2","3","4","5","6"]

然后，您可以执行以下操作：

files_names = ["1","2","3","4","5","6"]
data = ""
for file_name in files_names :
   with open(file_name+".json" ,"r") as file_handle :
      temp_data = file_handle.read()
      data = data + temp_data 

with open ('merged.json', 'a') as file_handle : 
  file_handle.write(data)

它更简洁、更具python风格，并且如果您需要7个json输入文件，就可以轻松地进行修改

• 如果您的文件总是1,2,3,4，那么您也可以这样做for循环迭代：知道您想要的最高json文件号

  max_file_name = 6
  for file_name in range(1,max_file_name):#i added 1 as first arg of 
  #range, assuming your files naming start at 1 and not at 0
     str(file_name) + ".json" 
  

• 为了确保Json是有效的Json，可以使用Json标准库。不过这需要更多的时间，因为文件将被解析，而不是直接转储到另一个文件中，但是如果您没有100000个文件要合并，并且您不确定在第一个plase中创建json文件的代码是否有效，那么您将看不到区别

  要想使用它，就去做吧

  import json
  max_file_name = 6
  data = ""
  for file_name in range(max_file_name):
     with open(str(file_name) + ".json" ,"r") as file_handle :
        temp_data = json.load(file_handle )
        data = {**data , **temp_data}
        # ** is used to "unload" every key value in a dict at runtime, 
        # as if you provided them one by one separated by comas :
        # data["key1"],data["key2"]...
        # doing so for both json objects and puttin them 
        # into a dictionnay is effectively just like merging them.
  
  with open ('merged.json', 'a') as file_handle : 
    json.dump(data,file_handle)
  

Answer 3

你有几种方法：

with open('a', 'w') as a, open('b', 'w') as b, ..:
    do_something()

---

files_list = ['a', 'b', ..]
for file in files_list:
    with open(file, 'w')...

---

使用contextlib.ExitStack

with ExitStack() as stack:
    files = [stack.enter_context(open(fname)) for fname in filenames]
    # Do something with "files"