我正在尝试使用Python2.7.5清理格式错误的CSV文件。CSV文件相当大(超过1GB)。文件的第一行正确地列出了列标题,但之后每个字段都在一个新行上(除非它是空的),有些字段是多行的。多行字段不被引号包围,但在输出中需要被引号包围。列的数目是静态的和已知的。提供的示例输入中的模式在整个文件长度内重复。
输入文件(示例):
Hostname,Username,IP Addresses,Timestamp,Test1,Test2,Test3
my_hostname
,my_username
,10.0.0.1
192.168.1.1
,2015-02-11 13:41:54 -0600
,,true
,false
my_2nd_hostname
,my_2nd_username
,10.0.0.2
192.168.1.2
,2015-02-11 14:04:41 -0600
,true
,,false
期望输出:
Hostname,Username,IP Addresses,Timestamp,Test1,Test2,Test3
my_hostname,my_username,"10.0.0.1 192.168.1.1",2015-02-11 13:41:54 -0600,,true,false
my_2nd_hostname,my_2nd_username,"10.0.0.2 192.168.1.2",2015-02-11 14:04:41 -0600,true,,false
我走了两条路,解决了其中一个问题,但我发现它不能处理格式错误的数据的另一个方面。如果有人能帮我找出一个有效的方法来清理这个文件,我将不胜感激。
谢谢
编辑
我从不同的路径得到了一些代码片段,但这里是当前的迭代。这不漂亮,只是一堆黑客试图解决这个问题。
import csv
inputfile = open('input.csv', 'r')
outputfile_1 = open('output.csv', 'w')
counter = 1
for line in inputfile:
#Skip header row
if counter == 1:
outputfile_1.write(line)
counter = counter + 1
else:
line = line.replace('\r', '').replace('\n', '')
outputfile_1.write(line)
inputfile.close()
outputfile_1.close()
with open('output.csv', 'r') as f:
text = f.read()
comma_count = text.count(',') #comma_count/6 = total number of rows
#need to insert a newline after the field contents after every 6th comma
#unfortunately the last field of the row and the first field of the next row are now rammed up together becaue of the newline replaces above...
#then process as normal CSV
#one path I started to go down... but this isn't even functional
groups = text.split(',')
counter2 = 1
while (counter2 <= comma_count/6):
line = ','.join(groups[:(6*counter2)]), ','.join(groups[(6*counter2):])
print line
counter2 = counter2 + 1
编辑2
感谢@DSM和@Ryan Vincent让我走上正轨。利用他们的想法,我做了下面的代码,这似乎纠正了我错误的CSV格式。我相信还有很多地方需要改进,我很乐意接受。
import csv
import re
outputfile_1 = open('output.csv', 'wb')
wr = csv.writer(outputfile_1, quoting=csv.QUOTE_ALL)
with open('input.csv', 'r') as f:
text = f.read()
comma_indices = [m.start() for m in re.finditer(',', text)] #Find all the commas - the fields are between them
cursor = 0
field_counter = 1
row_count = 0
csv_row = []
for index in comma_indices:
newrowflag = False
if "\r" in text[cursor:index]:
#This chunk has two fields, the last of one row and first of the next
next_field=text[cursor:index].split('\r')
next_field_trimmed = next_field[0].replace('\n',' ').rstrip().lstrip()
csv_row.extend([next_field_trimmed]) #Add the last field of this row
#Reset the cursor to be in the middle of the chuck (after the last field and before the next)
#And set a flag that we need to start the next csvrow before we move on to the next comma index
cursor = cursor+text[cursor:index].index('\r')+1
newrowflag = True
else:
next_field_trimmed = text[cursor:index].replace('\n',' ').rstrip().lstrip()
csv_row.extend([next_field_trimmed])
#Advance the cursor to the character after the comma to start the next field
cursor = index + 1
#If we've done 7 fields then we've finished the row
if field_counter%7==0:
row_count = row_count + 1
wr.writerow(csv_row)
#Reset
csv_row = []
#If the last chunk had 2 fields in it...
if newrowflag:
next_field_trimmed = next_field[1].replace('\n',' ').rstrip().lstrip()
csv_row.extend([next_field_trimmed])
field_counter = field_counter + 1
field_counter = field_counter + 1
#Write the last row
wr.writerow(csv_row)
outputfile_1.close()
# Process output.csv as normal CSV file...
这是关于我将如何处理这个问题的评论。
对于每一行:
我可以很容易地识别某些组的开始和结束:
注:我会使用“模式”匹配,使我能够确定我在正确的地方有正确的东西。它可以更快地发现错误。
从您的数据摘录看来,任何以逗号开头的行都需要连接到前一行,任何以逗号以外的任何行都将标记新行。
如果是这种情况,那么可以使用以下代码清理CSV文件,以便标准库
csv
解析器可以处理它。这是一个微型的国家机器。。。将行累加到每一行,直到找到一行不以逗号开头,然后写入前一行,依此类推。
相关问题 更多 >
编程相关推荐