Python CSV模块同时读写 [英] Python CSV Module read and write simultaneously

问题描述

我有两个.csv文件我在一个（文件a）中查找数据，并匹配到另一个（文件b）一旦我找到合适的行b我想写入相应行中的特定单元格。另外，我需要迭代这个，所以我可能会写入文件b中的每一行潜在几次。

我可以写一个csv文件，然后再读一遍吗？

  def match（name，group，cnum）：
 masterfile_list中的数据：
 if（data [0]中的名称）：
 if（group in data [4] ）：
 if（cnum ==112）：
 data [7] = cnum 
 elif（cnum ==111）：
 data [8] = cnum 
 elif（cnum ==110）：
 data [9] = cnum 
 elif（cnum ==109）：
 data [10] = cnum 
 elif（cnum ==108）：
 data [11] = cnum 
 elif（cnum ==107）：
 data [12] = cnum 
 elif（cnum ==106）：
 data [13] = cnum 
 elif（cnum ==105）：
 data [14] = cnum 
 elif cnum ==104）：
 data [15] = cnum 
 elif（cnum ==103）：
 data [16] = cnum 
 elif =102）：
 data [17] = cnum 
 elif（cnum ==101）：
 data [18] = cnum 
 
解决方案
 
 
 
 
 div> 
如果文件b不是非常大，我建议使用 readlines（）获得所有行的列表，然后遍历列表并根据需要更改行。这将比寻找文件中不同位置和替换行更容易一些。
 
 
 
此外，你可以显着减少函数体中的代码，我可能会做这样的事情：
  def match（name，group，cnum）：
 lookup = dict （map（str，range（112，100，-1）），range（7，19）））
 masterfile_list中的数据：
如果data [0] ]和cnum在查找：
 data [lookup [cnum]] = cnum 
  
 
I have two .csv files I am looking up data in one (file a) and matching it to the other (file b) once I find the appropriate row in b I want to write to a specific cell in the appropriate row.  Additionally I need to iterate over this so I will likely be writing to each row in file b potentially several times. 

can I write to a csv file and then read it over and over again?
def match(name, group, cnum):
  for data in masterfile_list:
    if (name in data[0]):
        if (group in data[4]):
            if (cnum == "112"):
                data[7] = cnum
            elif (cnum == "111"):
                data[8] = cnum
            elif (cnum == "110"):
                data[9] = cnum
            elif (cnum == "109"):
                data[10] = cnum
            elif (cnum == "108"):
                data[11] = cnum
            elif (cnum == "107"):
                data[12] = cnum
            elif (cnum == "106"):
                data[13] = cnum
            elif (cnum == "105"):
                data[14] = cnum
            elif (cnum == "104"):
                data[15] = cnum
            elif (cnum == "103"):
                data[16] = cnum
            elif (cnum == "102"):
                data[17] = cnum
            elif (cnum == "101"):
                data[18] = cnum 
I would ideally write/replace the line that matches.
解决方案
If file b is not extremely large I would suggest using readlines() to get a list of all lines and then iterate over the list and change lines as needed.  This will be quite a bit easier than seeking to different positions in the file and replacing lines.

Also, you can significantly reduce the code in the body of your function, I would probably do something like this:
def match(name, group, cnum):
    lookup = dict(zip(map(str, range(112, 100, -1)), range(7, 19)))
    for data in masterfile_list:
        if name in data[0] and group in data[4] and cnum in lookup:
            data[lookup[cnum]] = cnum


                        
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