I would like to make it so that it opens up alan.txt, search the text for all instance of scholary_tehologian and if found, add the word "test" under it. when I tried doing it this way:
## Script
with open('alan.txt', 'r+') as f:
for line in f:
if "scholarly_theologian" in line:
f.write("test")
it wouldn't write anything. I'm in Windows 8.1
You can't modify a file like this. You can only append to it, write characters instead of others, or rewrite it entirely. See How do I modify a text file in Python?.
What you should do is create another file with the content you want.
EDIT:
Claudio's answer has the code for what I offered. It has the benefit (over manicphase's code) of not keeping the whole file in memory. This is important if the file is long. manicphase's answer, on the other hand, has the benefit of not creating a second file. It rewrites the original one. Choose the one that fits your needs.
Rewritten answer because the last one was wrong.
If you want to read lines you have to put .readlines() after open(...) or f. Then there's a few ways you could insert "test".
## Script
with open('alan.txt', 'r') as f:
lines = f.readlines()
for i in range(len(lines)):
if "scholarly_theologian" in lines[i]:
lines[i] = lines[i] + "\ntest"
with open('alan.txt', 'w') as f:
f.write("\n".join(lines))
This should do the trick:
with open('output.txt', 'w') as o:
with open('alan.txt', 'r') as f:
for line in f:
o.write(line)
if line.find('scholarly_theoligian'):
o.write('test')
Like Ella Shar mentioned, you need to create a new file and add the new content into it.
If working with two files is not acceptable, the next step would be to delete the input file, and to rename the output file.
Related
I have a huge file. I've tried with other software, and it didn't work. So I want to make a custom script.
However, I just cannot work it out myself.
I want to delete every line in a file with the following condition: if "[" in line:
File in question is a .txt file with about 14,000,000 lines. I would prefer something fast.
I've tried other similar functions on this page, but I couldn't find any that would fit my requirements.
Instead of deleting, you can pretty easily make a copy of the file with only the desired records.
in_file_path = 'xxxx'
out_file_path = 'yyyy'
with open(in_file_path, 'r') as fh_in:
with open(out_file_path, 'w') as fh_out:
for line in fh_in:
if not '[' in line:
fh_out.write(line)
If you want to go even faster, you can read and write in binary mode and check for b'[' in the line.
Use the readline method of the file object inside a while loop. So while you are in the loop get all lines that do not fit the if condition and store into into a data structure.
Later open a new file and write th entire structure to the new file
Try this. This is a simple read and write of a file:
with open("sample_file.txt", "r") as reader:
new_file = []
for line in reader:
if "[" not in line:
new_file.append(line)
with open("new_file.txt", "w+") as writer:
writer.writelines(new_file)
I want to load/read a text file and write it to two other text files "entirely". I will write other different data to the following of these two files later.
The problem is that the loaded file is only written to the first file, and no data from that loaded file is written to the second file.
The code I am using:
fin = open("File_Read", 'r')
fout1 = open("File_Write1", 'w')
fout2 = open("File_Write2", 'w')
fout1.write(fin.read())
fout2.write(fin.read()) #Nothing is written here!
fin.close()
fout1.close()
fout2.close()
What is happening and what is the solution?
I prefer using open instead of with open.
Thanks.
Apparently the fin.read() reads all the lines, the next fin.read() will continue from where the previous .read() ended (which is the last line). To solve this, I would simply go for:
text_fin = fin.read()
fout1.write(text_fin)
fout2.write(text_fin)
fin = open("test.txt", 'r')
data = fin.read()
fin.close()
fout1 = open("test2.txt", 'w')
fout1.write(data)
fout1.close()
fout2 = open("test3.txt", 'w')
fout2.write(data)
fout2.close()
N.B. with open is the safest and best way but at least you need to close the file as soon as there are not needed anymore.
You can try iterating through your original file line by line and appending it to both the files. You are running into the problem because file.write() method takes string argument.
fin = open("File_Read",'r')
fout1 = open("File_Write1",'a') #append permissions for line-by-line writing
fout2 = open("File_Write2",'a') #append permissions for line-by-line writing
for lines in fin:
fout1.write(lines)
fout2.write(lines)
fin.close()
fout1.close()
fout2.close()
*** NOTE: Not the most efficient solution.
Similar to posting: Replace string in a specific line using python, however results were not forethcomming in my slightly different instance.
I working with python 3 on windows 7. I am attempting to batch edit some files in a directory. They are basically text files with .LIC tag. I'm not sure if that is relevant to my issue here. I am able to read the file into python without issue.
My aim is to replace a specific string on a specific line in this file.
import os
import re
groupname = 'Oldtext'
aliasname = 'Newtext'
with open('filename') as f:
data = f.readlines()
data[1] = re.sub(groupname,aliasname, data[1])
f.writelines(data[1])
print(data[1])
print('done')
When running the above code I get an UnsupportedOperation: not writable. I am having some issue writing the changes back to the file. Based on suggestion of other posts, I edited added the w option to the open('filename', "w") function. This causes all text in the file to be deleted.
Based on suggestion, the r+ option was tried. This leads to successful editing of the file, however, instead of editing the correct line, the edited line is appended to the end of the file, leaving the original intact.
Writing a changed line into the middle of a text file is not going to work unless it's exactly the same length as the original - which is the case in your example, but you've got some obvious placeholder text there so I have no idea if the same is true of your actual application code. Here's an approach that doesn't make any such assumption:
with open('filename', 'r') as f:
data = f.readlines()
data[1] = re.sub(groupname,aliasname, data[1])
with open('filename', 'w') as f:
f.writelines(data)
EDIT: If you really wanted to write only the single line back into the file, you'd need to use f.tell() BEFORE reading the line, to remember its position within the file, and then f.seek() to go back to that position before writing.
I would like to know how to overwrite a file in python. When I'm using "w" in the open statement, I still get only one line in my output file.
article = open("article.txt", "w")
article.write(str(new_line))
article.close()
Can you tell me please how can I fix my problem?
If you are in fact looking to overwrite the file line by line, you'll have to do some additional work - since the only modes available are read ,write and append, neither of which actually do a line-by-line overwrite.
See if this is what you're looking for:
# Write some data to the file first.
with open('file.txt', 'w') as f:
for s in ['This\n', `is a\n`, `test\n`]:
f.write(s)
# The file now looks like this:
# file.txt
# >This
# >is a
# >test
# Now overwrite
new_lines = ['Some\n', 'New data\n']
with open('file.txt', 'a') as f:
# Get the previous contents
lines = f.readlines()
# Overwrite
for i in range(len(new_lines)):
f.write(new_lines[i])
if len(lines) > len(new_lines):
for i in range(len(new_lines), len(lines)):
f.write(lines[i])
As you can see, you first need to 'save' the contents of the file in a buffer (lines), and then replace that.
The reason for that is how the file modes work.
"overwrite" is a strange term; especially since you expect to see more than one line from the above code
I am guessing you mean something like "write beyond". The word for that would be "append' and you would want 'a' instead of 'w'.
I have a file named a.txt which looks like this:
I'm the first line
I'm the second line.
There may be more lines here.
I'm below an empty line.
I'm a line.
More lines here.
Now, I want to remove the contents above the empty line(including the empty line itself).
How could I do this in a Pythonic way?
Basically you can't delete stuff from the beginning of a file, so you will have to write to a new file.
I think the pythonic way looks like this:
# get a iterator over the lines in the file:
with open("input.txt", 'rt') as lines:
# while the line is not empty drop it
for line in lines:
if not line.strip():
break
# now lines is at the point after the first paragraph
# so write out everything from here
with open("output.txt", 'wt') as out:
out.writelines(lines)
Here are some simpler versions of this, without with for older Python versions:
lines = open("input.txt", 'rt')
for line in lines:
if not line.strip():
break
open("output.txt", 'wt').writelines(lines)
and a very straight forward version that simply splits the file at the empty line:
# first, read everything from the old file
text = open("input.txt", 'rt').read()
# split it at the first empty line ("\n\n")
first, rest = text.split('\n\n',1)
# make a new file and write the rest
open("output.txt", 'wt').write(rest)
Note that this can be pretty fragile, for example windows often uses \r\n as a single linebreak, so a empty line would be \r\n\r\n instead. But often you know the format of the file uses one kind of linebreaks only, so this could be fine.
Naive approach by iterating over the lines in the file one by one top to bottom:
#!/usr/bin/env python
with open("4692065.txt", 'r') as src, open("4692065.cut.txt", "w") as dest:
keep = False
for line in src:
if keep: dest.write(line)
if line.strip() == '': keep = True
The fileinput module (from the standard library) is convenient for this kind of thing. It sets things up so you can act as though your are editing the file "in-place":
import fileinput
import sys
fileobj=iter(fileinput.input(['a.txt'], inplace=True))
# iterate through the file until you find an empty line.
for line in fileobj:
if not line.strip():
break
# Iterators (like `fileobj`) pick up where they left off.
# Starting a new for-loop saves you one `if` statement and boolean variable.
for line in fileobj:
sys.stdout.write(line)
Any idea how big the file is going to be?
You could read the file into memory:
f = open('your_file', 'r')
lines = f.readlines()
which will read the file line by line and store those lines in a list (lines).
Then, close the file and reopen with 'w':
f.close()
f = open('your_file', 'w')
for line in lines:
if your_if_here:
f.write(line)
This will overwrite the current file. Then you can pick and choose which lines from the list you want to write back in. Probably not a very good idea if the file gets to large though, since the entire file has to reside in memory. But, it doesn't require that you create a second file to dump your output.
from itertools import dropwhile, islice
def content_after_emptyline(file_object):
return islice(dropwhile(lambda line: line.strip(), file_object), 1, None)
with open("filename") as f:
for line in content_after_emptyline(f):
print line,
You could do a little something like this:
with open('a.txt', 'r') as file:
lines = file.readlines()
blank_line = lines.index('\n')
lines = lines[blank_line+1:] #\n is the index of the blank line
with open('a.txt', 'w') as file:
file.write('\n'.join(lines))
and that makes the job much simpler.