csv阅读器输出多余的空白项目

问题描述

我有一个输入csv，其中包含要尝试进入列表的可变列数.我的测试是解析输入的csv，并在csv列周围创建一个包含额外元素的列表.我想看到的是仅包含csv元素的列表，而且我也得到了空的带引号的元素.我需要一些帮助，以了解缺少的CSV阅读器的哪些选项.

I have an input csv with a variable number of columns I'm trying to pull into a list. My test is parsing the input csv and creating a list with extra elements around the csv columns. What I would like to see is a list that contains only the csv elements, and I'm getting empty quoted elements as well. I need some help understanding what options to the csv reader I'm missing.

示例输出:

$ python cond.py
opening conditions file  conditions.lst
parser  0  input line:
"string1:", "string1b,string1c,"
output list elements:
['string1:']
['', '']
['']
['string1b,string1c,']
[]

parser  1  input line:
"stringa:", "stringb,stringc,"
output list elements:
['stringa:']
['', '']
['']
['stringb,stringc,']
[]

parser  2  input line:
"string3:", "string3next=abc", "string3b","string3c:", "string3d"
output list elements:
['string3:']
['', '']
['']
['string3next=abc']
['', '']
['']
['string3b']
['', '']
['string3c:']
['', '']
['']
['string3d']
[]

输入文件:

$ cat conditions.lst
"string1:", "string1b,string1c,"
"stringa:", "stringb,stringc,"
"string3:", "string3next=abc", "string3b","string3c:", "string3d"

Python cond.py文件:

Python cond.py file:

$ cat cond.py

from __future__ import print_function
#from csv import reader

import re
import sys
import csv

# variables

conditionsFile = "conditions.lst"
parserConditions = []
numOfParsers = 0


print("opening conditions file ", conditionsFile)
with open(conditionsFile, "r") as cf:
  for line in cf:
    print("parser ", numOfParsers, " input line:")
    print(line.strip())

    r = csv.reader(line, quotechar='"', delimiter=',', quoting=csv.QUOTE_ALL, skipinitialspace=True)
    print("output list elements:")
    for cline in  r:
      print(cline)

    numOfParsers = numOfParsers + 1
    print("")

  print("total number of parsers: ", numOfParsers)

更新:在@Jean-FrançoisFabre的帮助下，我尚未解决根本原因，但有了解决方法-我将csv元素放入列表中，然后删除了空白元素.

Update:Using help from @Jean-FrançoisFabre I haven't solved the root reason but have got a workaround - I put the csv elements into a list then remove the blank elements.

for cline in  r:
  conditions.extend(cline)

conditions = filter(None, conditions)
print(conditions)

推荐答案

csv.reader接受类似于文件的对象，而不是字符串...因此，它奇怪地遍历了行的字符而不是文件的行.您只需要:

csv.reader takes a file-like object not a string...so it is iterating strangely over the characters of a line instead of the lines of a file. You just need:

from __future__ import print_function
import csv

with open('conditions.lst','rb') as cf:
    r = csv.reader(cf,skipinitialspace=True)
    for line in r:
        print(line)

输出:

['string1:', 'string1b,string1c,']
['stringa:', 'stringb,stringc,']
['string3:', 'string3next=abc', 'string3b', 'string3c:', 'string3d']

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