python - csv阅读器输出额外的空白项
问题描述
我有一个输入 csv,其中包含可变数量的列,我试图将其拉入列表。我的测试是解析输入 csv 并在 csv 列周围创建一个包含额外元素的列表。我想看到的是一个只包含 csv 元素的列表,而且我也得到了空的引用元素。我需要一些帮助来了解我缺少的 csv 阅读器的哪些选项。
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:
$ 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:使用@Jean-FrançoisFabre 的帮助我没有解决根本原因,但有一个解决方法 - 我将 csv 元素放入列表中,然后删除空白元素。
for cline in r:
conditions.extend(cline)
conditions = filter(None, conditions)
print(conditions)
解决方案
csv.reader
接受一个类似文件的对象而不是字符串......所以它奇怪地迭代一行的字符而不是文件的行。您只需要:
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']