使用 Python 解析文本文件

Question

我正在尝试解析一系列文本文件并使用 Python (2.7.3) 将它们保存为 CSV 文件。所有文本文件都有一个 4 行长的标题，需要将其删除。数据行有各种分隔符，包括“（引号）、-（破折号）、: 列和空格。我发现使用所有这些不同的分隔符在 C++ 中编写代码很痛苦，所以我决定在 Python 中试一试与 C/C++ 相比，它相对容易实现。

我写了一段代码来测试它是否适用于单行数据并且它有效，但是，我无法设法让它适用于实际文件。为了解析一行，我使用了文本对象和“替换”方法。看起来我当前的实现将文本文件作为列表读取，并且列表对象没有替换方法。

作为 Python 的新手，我被困在了这一点上。任何输入将不胜感激！

谢谢！

 # function for parsing the data
def data_parser(text, dic):
for i, j in dic.iteritems():
    text = text.replace(i,j)
return text

# open input/output files

inputfile = open('test.dat')
outputfile = open('test.csv', 'w')

my_text = inputfile.readlines()[4:] #reads to whole text file, skipping first 4 lines

# sample text string, just for demonstration to let you know how the data looks like
# my_text = '"2012-06-23 03:09:13.23",4323584,-1.911224,-0.4657288,-0.1166382,-0.24823,0.256485,"NAN",-0.3489428,-0.130449,-0.2440527,-0.2942413,0.04944348,0.4337797,-1.105218,-1.201882,-0.5962594,-0.586636'

# dictionary definition 0-, 1- etc. are there to parse the date block delimited with dashes, and make sure the negative numbers are not effected
reps = {'"NAN"':'NAN', '"':'', '0-':'0,','1-':'1,','2-':'2,','3-':'3,','4-':'4,','5-':'5,','6-':'6,','7-':'7,','8-':'8,','9-':'9,', ' ':',', ':':',' }

txt = data_parser(my_text, reps)
outputfile.writelines(txt)

inputfile.close()
outputfile.close()

原文由 marillion 发布，翻译遵循 CC BY-SA 4.0 许可协议

Answer 1

我会使用 for 循环来遍历文本文件中的行：

 for line in my_text:
    outputfile.writelines(data_parser(line, reps))

如果你想逐行读取文件而不是在脚本开头加载整个文件，你可以这样做：

 inputfile = open('test.dat')
outputfile = open('test.csv', 'w')

# sample text string, just for demonstration to let you know how the data looks like
# my_text = '"2012-06-23 03:09:13.23",4323584,-1.911224,-0.4657288,-0.1166382,-0.24823,0.256485,"NAN",-0.3489428,-0.130449,-0.2440527,-0.2942413,0.04944348,0.4337797,-1.105218,-1.201882,-0.5962594,-0.586636'

# dictionary definition 0-, 1- etc. are there to parse the date block delimited with dashes, and make sure the negative numbers are not effected
reps = {'"NAN"':'NAN', '"':'', '0-':'0,','1-':'1,','2-':'2,','3-':'3,','4-':'4,','5-':'5,','6-':'6,','7-':'7,','8-':'8,','9-':'9,', ' ':',', ':':',' }

for i in range(4): inputfile.next() # skip first four lines
for line in inputfile:
    outputfile.writelines(data_parser(line, reps))

inputfile.close()
outputfile.close()

原文由 Joe Day 发布，翻译遵循 CC BY-SA 3.0 许可协议

Answer 2

从接受的答案来看，您想要的行为似乎是转向

skip 0
skip 1
skip 2
skip 3
"2012-06-23 03:09:13.23",4323584,-1.911224,-0.4657288,-0.1166382,-0.24823,0.256485,"NAN",-0.3489428,-0.130449,-0.2440527,-0.2942413,0.04944348,0.4337797,-1.105218,-1.201882,-0.5962594,-0.586636

进入

2012,06,23,03,09,13.23,4323584,-1.911224,-0.4657288,-0.1166382,-0.24823,0.256485,NAN,-0.3489428,-0.130449,-0.2440527,-0.2942413,0.04944348,0.4337797,-1.105218,-1.201882,-0.5962594,-0.586636

如果那是对的，那么我想是这样的

import csv

with open("test.dat", "rb") as infile, open("test.csv", "wb") as outfile:
    reader = csv.reader(infile)
    writer = csv.writer(outfile, quoting=False)
    for i, line in enumerate(reader):
        if i < 4: continue
        date = line[0].split()
        day = date[0].split('-')
        time = date[1].split(':')
        newline = day + time + line[1:]
        writer.writerow(newline)

会比 reps 东西简单一点。

原文由 DSM 发布，翻译遵循 CC BY-SA 3.0 许可协议