Find and replace within a text file using Python

Question

I have a text file which is about 400,000 lines long. I need to import this text file into a program which only accepts text files which are delimited with spaces or tabs, but this text file is delimited with semi-colons. There is no option in the program I am exporting the text file from (Arcmap) to change the delimination and doing find and replace in the text file itself will literally take 2 days.

I have searched for a script to do this but they all seem to replace the whole LINE of the word file with a space, instead of individually replacing each semi-colon, Leaving me with an empty text file.

Here is a sample of my text file:

"OID_";"POINTID";"GRID_CODE";"POINT_X";"POINT_Y"
;1;-56.000000;200900.250122;514999.750122
;2;-56.000000;200900.750122;514999.750122
;3;-56.000000;200901.250122;514999.750122
;4;-57.000000;200901.750122;514999.750122
;5;-57.000000;200902.250122;514999.750122
;6;-57.000000;200902.750122;514999.750122
;7;-57.000000;200903.250122;514999.750122
;8;-57.000000;200903.750122;514999.750122
;9;-57.000000;200904.250122;514999.750122
;10;-57.000000;200904.750122;514999.750122

I need it to look something like this:

1 -56.000000 200900.250122 514999.750122
2 -56.000000 200900.750122 514999.750122

Alice, please edit your question to show (1) the first few lines of your file (2) what those lines should look like after fixing. I'm fairly certain that we can help you, but we need to know exactly what you need to do. Also, Python 2.x or 3.X? — John Machin
– John Machin, Commented Jan 20, 2011 at 10:56
I need a python solution because doing it with the "find replace all" funcion in notepad causes my computer to compust! — Alice Duff
– Alice Duff, Commented Jan 20, 2011 at 11:00
John, i will edit it now.. it takes about 10 minutes to open the file though!! — Alice Duff
– Alice Duff, Commented Jan 20, 2011 at 11:02
Alice, (1) PLEASE answer: Python 2.X or 3.X? (2) Please start ANOTHER question with the file rename problem (and delete it from this question) — John Machin
– John Machin, Commented Jan 20, 2011 at 11:05
Alice, are you SURE that there are TWO logical records per line??? What is the significance of the leading ;?? Are there in fact any line breaks at all??? — John Machin
– John Machin, Commented Jan 20, 2011 at 11:10

eumiro · Accepted Answer · 2011-01-20 11:12:19Z

33

How about this:

sed -i 's/;/ /g' yourBigFile.txt

This is not a Python solution. You have to start this in a shell. But if you use Notepad, I guess you are on Windows. So here a Python solution:

f1 = open('yourBigFile.txt', 'r')
f2 = open('yourBigFile.txt.tmp', 'w')
for line in f1:
    f2.write(line.replace(';', ' '))
f1.close()
f2.close()

edited Jan 20, 2011 at 11:12

answered Jan 20, 2011 at 10:55

eumiro

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4 Comments

Alice Duff Over a year ago

just copy this straight into python? Do i have to write anything infront of it (sorry for my complete uselessness!)

eumiro Over a year ago

@Alice, I have added a Python solution for you

Alice Duff Over a year ago

I get the error: Message File Name Line Position Traceback <module> C:\Documents and Settings\DuffA\Mijn documenten\Downloads\search_replace.py 6 AttributeError: 'file' object has no attribute 'replace'

maudulus Over a year ago

This is better: stackoverflow.com/questions/25940101/…

Mark Booth · Accepted Answer · 2012-03-06 15:02:41Z

21

with Python, you can use fileinput.

import fileinput
for line in fileinput.FileInput("file",inplace=1):
    line = line.replace(";"," ")
    print line,

this will replace all your ";" to spaces in place.

edited Mar 6, 2012 at 15:02

Mark Booth

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answered Jan 20, 2011 at 11:23

ghostdog74

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3 Comments

satnhak Over a year ago

That adds an extra line break after every line for me in Windows.

Mark Booth Over a year ago

@TheMouthofaCow - I've suggested an edit to fix that problem.

maudulus Over a year ago

This solves the extra line problem: stackoverflow.com/questions/25940101/…

Community · Accepted Answer · 2017-05-23 12:17:48Z

4

Python 3.2 has added ability to use this as context manager, so that the files that fail during processing for some reason will always get closed:

import fileinput
def main():
    with fileinput.input(inplace=True) as f:
        for line in f:
            line = line.replace(";", " ")
            print(line, end='')

(inspiration)

Use it by supplying it with the text file you want to process.

edited May 23, 2017 at 12:17

CommunityBot

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answered Jan 6, 2013 at 15:22

tshepang

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2 Comments

David Doria Over a year ago

Tshepang What does this line do? print(line, end='')

tshepang Over a year ago

"insert an empty string at the end of the line, instead of the usual \n character"

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