在字符串周围用引号编写csv（Python）

Question

我编写了以下代码来获取一个大型 csv 文件，并根据列中的特定单词将其拆分为多个 csv 文件。原始的 csv 文件有一些字段是字符串，并且它们周围有引号。

例如：

Field1,Field2,Field3,Field4
1,2,"red",3
1,4,"red",4
3,4,"blue",4

等等

我的代码根据 Field4 将文件拆分为单独的 csv。

我的输出如下所示：

3.csv
Field1,Field2,Field3,Field4
1,2,red,3

4.csv
Field1,Field2,Field3,Field4
1,4,red,4
3,4,blue,4

我希望我的输出在字段 3 中的字符串周围保持引号。文件被输入到一个软件中，该软件仅在字符串周围有引号时才有效，这很烦人。

我当前的代码如下所示：

import csv

#Creates empty set - this will be used to store the values that have already been used
newfilelist = set()

#Opens the large csv file in "read" mode
with open('File.csv', 'r') as csvfile:
    
    #Read the first row of the large file and store the whole row as a string (headerstring)
    read_rows = csv.reader(csvfile)
    headerrow = next(read_rows)
    headerstring=','.join(headerrow) 
    for row in read_rows:
        
        #Store the whole row as a string (rowstring)
        rowstring=','.join(row)
        
        #Takes Field 4
        newfilename = (row[3])
        
        
        #This basically makes sure it is not looking at the header row.
        if newfilename != "field4":
        
            
            #If the newfilename is not in the newfilename set, add it to the list and create new csv file with header row.
            if newfilename not in newfilelist:    
                newfilelist.add(newfilename)
                with open('//output/' +str(newfilename)+'.csv','a') as f:
                    f.write(headerstring)
                    f.write("\n")
                    f.close()    
            #If the newfilename is in the newfilelist set, append the current row to the existing csv file.     
            else:
                with open('//output/' +str(newfilename)+'.csv','a') as f:
                    f.write(rowstring)
                    f.write("\n")
                    f.close()
 

谁能告诉我如何得到字符串周围的引号？不幸的是，使用我的文件的软件要求它们采用这种格式！

Answer 1

将quoting=csv.QUOTE_NONNUMERIC 传递给csv.writer()。

Answer 2

CSVwriter 对于您正在尝试做的事情可能有点矫枉过正。如果您希望整行保持不变，只需写整行即可。

#Creates empty array - this will be used to store the values that have already been used
newfilelist = {}

#Opens the large csv file in "read" mode
with open('File.csv, 'r') as csvfile:

    #Read the first row of the large file and store the whole row as a string (headerstring)
    headerstring = csvfile.readline()
    for row in csvfile.readlines():

        #Takes Field 4
        newfilename = row.split(',')[3].strip('"')

        #If the newfilename is not in the newfilename set, add it to the list and create new csv file with header row.
        if newfilename not in newfilelist:    
            newfilelist[newfilename] = open('//output/' +str(newfilename)+'.csv','w'):  #open a file and store the file reference in an dictionary
            newfilelist[newfilename].write(headerstring)

        newfilelist[newfilename].write(row)  # Write out a row to an existing file

#Close all open files
for k in newfilelist.keys():
    newfilelist[k].close()