Question

我正在清理csv文件中的非分隔符逗号。我有3个python片段，它们以交互方式工作以更改分隔符，替换逗号并重新实例化逗号分隔符。重新测试后，我发现这个单一的脚本不起作用，我想对在单个脚本中运行这些脚本的最佳实践方法有一些反馈。

#!/usr/bin/env python
# changes delimiter 
import csv      
reader = csv.reader(open("commas.csv", "rU"), delimiter=',')
writer = csv.writer(open("commas2.csv", 'w'), delimiter=';')
writer.writerows(reader)
quit()

# replaces commas with spaces           
s = open("commas2.csv").read()
s = s.replace(',', ' ')
f = open("commas3.csv", 'w')
f.write(s)
f.close()
quit()

# changes delimiter back to commas
import csv
reader = csv.reader(open("commas3.csv", "rU"), delimiter=';')
writer = csv.writer(open("commas4.csv", 'w'), delimiter=',')
writer.writerows(reader)     
quit()

Answer 1

正如你所说，你需要使用with语句来正确关闭所有文件（好吧，你不需要，但这是最佳做法）：

import csv
with open("commas.csv", "r") as fr:
    with open("commas2.csv", "w") as fw:
        reader = csv.reader(fr, delimiter=',')
        writer = csv.writer(fw, delimiter=';')
        writer.writerows(reader)


with open("commas2.csv", "r") as fr:
    s = fr.read()
with open("commas3.csv", "w") as fw:
    fw.write(s.replace(",", " "))

# changes delimiter back to commas
with open("commas3.csv", "r") as fr:
    with open("commas4.csv", "w") as fw:
        reader = csv.reader(fr, delimiter=';')
        writer = csv.writer(fw, delimiter=',')
        writer.writerows(reader)

但你可以通过文件一次传递来做到这一点，因为你已经在内存中拥有了所有的csv内容，你可以逐个单元地修改它们，而不是用不同的分隔符保存它们然后再更改分隔符：

import csv

with open("commas.csv", "r") as f:
    reader = csv.reader(f)
    new_data = [] # new csv 2d array
    for line in reader:
        l = list()
        for cell in line: # go over every cell
            l.append(cell.replace(",", " ")) # replace commas then save it to new array
        new_data.append(l)

with open("commas2.csv", "w") as f:
    writer = csv.writer(f)
    writer.writerows(new_data)

从交互式代码段创建python脚本

1 个答案: