write to previous line in python - python

I am writing code to generate words from one file to another
I have done all ok but the problem that when I use line it feed a new line in the output file I want to next word after line to be written at the same line
the code
with open("test.txt") as f:
with open("out.txt", "w") as f1:
for line in f:
f1.write("<answer>" + line +"doit");
now doit comes in a new line in the out.txt
the text file has 3 lines
door
window
house

The problem is that your variable line contains a \n at the end, which you have to remove yourself:
with open("test.txt") as f:
with open("out.txt", "w") as f1:
for line in f:
f1.write("<answer>" + line[:-1] +"doit")
The problem of using rstrip as the other answer suggests is that you would lose ending spaces: ' aa \n'.rstrip() gives you ' aa'. This might or might not be what you need.

Use rstrip() to remove the trailing \n
with open("test.txt") as f:
with open("out.txt", "w") as f1:
for line in f:
f1.write("<answer>" + line.rstrip('\n') +"doit");

Related

Trying to remove multiple space in txt file using python [duplicate]

So I have this crazy long text file made by my crawler and it for some reason added some spaces inbetween the links, like this:
https://example.com/asdf.html (note the spaces)
https://example.com/johndoe.php (again)
I want to get rid of that, but keep the new line. Keep in mind that the text file is 4.000+ lines long. I tried to do it myself but figured that I have no idea how to loop through new lines in files.
Seems like you can't directly edit a python file, so here is my suggestion:
# first get all lines from file
with open('file.txt', 'r') as f:
lines = f.readlines()
# remove spaces
lines = [line.replace(' ', '') for line in lines]
# finally, write lines in the file
with open('file.txt', 'w') as f:
f.writelines(lines)
You can open file and read line by line and remove white space -
Python 3.x:
with open('filename') as f:
for line in f:
print(line.strip())
Python 2.x:
with open('filename') as f:
for line in f:
print line.strip()
It will remove space from each line and print it.
Hope it helps!
Read text from file, remove spaces, write text to file:
with open('file.txt', 'r') as f:
txt = f.read().replace(' ', '')
with open('file.txt', 'w') as f:
f.write(txt)
In #Leonardo Chirivì's solution it's unnecessary to create a list to store file contents when a string is sufficient and more memory efficient. The .replace(' ', '') operation is only called once on the string, which is more efficient than iterating through a list performing replace for each line individually.
To avoid opening the file twice:
with open('file.txt', 'r+') as f:
txt = f.read().replace(' ', '')
f.seek(0)
f.write(txt)
f.truncate()
It would be more efficient to only open the file once. This requires moving the file pointer back to the start of the file after reading, as well as truncating any possibly remaining content left over after you write back to the file. A drawback to this solution however is that is not as easily readable.
I had something similar that I'd been dealing with.
This is what worked for me (Note: This converts from 2+ spaces into a comma, but if you read below the code block, I explain how you can get rid of ALL whitespaces):
import re
# read the file
with open('C:\\path\\to\\test_file.txt') as f:
read_file = f.read()
print(type(read_file)) # to confirm that it's a string
read_file = re.sub(r'\s{2,}', ',', read_file) # find/convert 2+ whitespace into ','
# write the file
with open('C:\\path\\to\\test_file.txt', 'w') as f:
f.writelines('read_file')
This helped me then send the updated data to a CSV, which suited my need, but it can help for you as well, so instead of converting it to a comma (','), you can convert it to an empty string (''), and then [or] use a read_file.replace(' ', '') method if you don't need any whitespaces at all.
Lets not forget about adding back the \n to go to the next row.
The complete function would be :
with open(str_path, 'r') as file :
str_lines = file.readlines()
# remove spaces
if bl_right is True:
str_lines = [line.rstrip() + '\n' for line in str_lines]
elif bl_left is True:
str_lines = [line.lstrip() + '\n' for line in str_lines]
else:
str_lines = [line.strip() + '\n' for line in str_lines]
# Write the file out again
with open(str_path, 'w') as file:
file.writelines(str_lines)

To split and save text in a file using python

Below is the input file sample_text.txt
10001ScottTiher100040
10002ScoteTijer100042
10003ScotrTieer100043
10004ScotfTiler100044
10005ScotyTiper100046
10006ScotlTioer100047
10007ScotiTiwer100049
I need to save this in the same file as below, can you please help me on this....
10001,Scott,Tiher,100040
10002,Scote,Tijer,100042
10003,Scotr,Tieer,100043
10004,Scotf,Tiler,100044
10005,Scoty,Tiper,100046
10006,Scotl,Tioer,100047
10007,Scoti,Tiwer,100049
I have tried the below code, but unable to save the b in new file or same file
with open('D:\Programs\python\sql_test.txt','r+') as f:
for line in f:
for word in line.split():
b = str(word[0:5])+ ',' + str(word[5:10]) + ',' + str(word[10:15])+','+ str(word[15:21])
print(b)
You can open two file with with context manager: One for input, The other for output.
with open("ifilename", 'r') as ifile, open("ofilename", 'w') as ofile:
for line in ifile:
print(','.join([line[0:5], line[5:10], line[10:15], line[15:]]), file=ofile)
This is one approach
Demo:
res = []
with open(filename, "r") as infile:
for i in infile.readlines():
val = i.strip()
res.append([val[:5], val[5:10], val[10:15], val[15:]])
with open(filename, "w") as outfile:
for i in res:
outfile.write(", ".join(i) + "\n")
Maybe the reg is simple to do this:
import re
with open("origin.txt", 'r') as in_fd, open("new.txt", 'w') as out_fd:
for line in in_fd.readlines():
match = re.match(r"([0-9]+)([a-z]+)([0-9]+)", line, re.I)
out_fd.write(','.join(match.groups())+ '\n')
You have to use f.write(b) to save b in your file
Very late answer
Your early solution is better without the second loop.
As you know, you cannot have a file with the read option (r) and also the write (w) option.
The option r+, append the transformed data to the end of the file. For the sake of the exercice, we will not use r+
Here, we use f to read the file and f1 to write the results, ending with a formatting with a \n to jump lines.
In [3]: with open('split.txt','r') as f, open('split2.txt','w') as f1: #one file for read and the other one for saving the result
...: for line in f:
...: output = str(line[0:5])+ ',' + str(line[5:10]) + ',' + str(line[10:15])+','+ str(line[15:21])
...: f1.write("{0}{1}".format(output,"\n")) #outputting with \n to jump to the next line for any new line

Removing all spaces in text file with Python 3.x

So I have this crazy long text file made by my crawler and it for some reason added some spaces inbetween the links, like this:
https://example.com/asdf.html (note the spaces)
https://example.com/johndoe.php (again)
I want to get rid of that, but keep the new line. Keep in mind that the text file is 4.000+ lines long. I tried to do it myself but figured that I have no idea how to loop through new lines in files.
Seems like you can't directly edit a python file, so here is my suggestion:
# first get all lines from file
with open('file.txt', 'r') as f:
lines = f.readlines()
# remove spaces
lines = [line.replace(' ', '') for line in lines]
# finally, write lines in the file
with open('file.txt', 'w') as f:
f.writelines(lines)
You can open file and read line by line and remove white space -
Python 3.x:
with open('filename') as f:
for line in f:
print(line.strip())
Python 2.x:
with open('filename') as f:
for line in f:
print line.strip()
It will remove space from each line and print it.
Hope it helps!
Read text from file, remove spaces, write text to file:
with open('file.txt', 'r') as f:
txt = f.read().replace(' ', '')
with open('file.txt', 'w') as f:
f.write(txt)
In #Leonardo Chirivì's solution it's unnecessary to create a list to store file contents when a string is sufficient and more memory efficient. The .replace(' ', '') operation is only called once on the string, which is more efficient than iterating through a list performing replace for each line individually.
To avoid opening the file twice:
with open('file.txt', 'r+') as f:
txt = f.read().replace(' ', '')
f.seek(0)
f.write(txt)
f.truncate()
It would be more efficient to only open the file once. This requires moving the file pointer back to the start of the file after reading, as well as truncating any possibly remaining content left over after you write back to the file. A drawback to this solution however is that is not as easily readable.
I had something similar that I'd been dealing with.
This is what worked for me (Note: This converts from 2+ spaces into a comma, but if you read below the code block, I explain how you can get rid of ALL whitespaces):
import re
# read the file
with open('C:\\path\\to\\test_file.txt') as f:
read_file = f.read()
print(type(read_file)) # to confirm that it's a string
read_file = re.sub(r'\s{2,}', ',', read_file) # find/convert 2+ whitespace into ','
# write the file
with open('C:\\path\\to\\test_file.txt', 'w') as f:
f.writelines('read_file')
This helped me then send the updated data to a CSV, which suited my need, but it can help for you as well, so instead of converting it to a comma (','), you can convert it to an empty string (''), and then [or] use a read_file.replace(' ', '') method if you don't need any whitespaces at all.
Lets not forget about adding back the \n to go to the next row.
The complete function would be :
with open(str_path, 'r') as file :
str_lines = file.readlines()
# remove spaces
if bl_right is True:
str_lines = [line.rstrip() + '\n' for line in str_lines]
elif bl_left is True:
str_lines = [line.lstrip() + '\n' for line in str_lines]
else:
str_lines = [line.strip() + '\n' for line in str_lines]
# Write the file out again
with open(str_path, 'w') as file:
file.writelines(str_lines)

Writing a new text file in python

I'm writing code that goes over a text file counting how many words are in every line and having trouble putting the result (many lines that each consist ofa number) into a new text file.
My code:
in_file = open("our_input.txt")
out_file = open("output.txt", "w")
for line in in_file:
line = (str(line)).split()
x = (len(line))
x = str(x)
out_file.write(x)
in_file.close()
out_file.close()
But the file I'm getting has all the number together in one line.
How do I seperate them in the file I'm making?
You need to add a new line after each line :
out_file.write(x + '\n')
Also as a more pythonic way for dealing with files you can use with statement to open the files which will close the files at the end of the block.
And instead of multiple assignment and converting the length to string you can use str.format() method to do all of this jobs in one line:
with open("our_input.txt") as in_file,open("output.txt", "w") as out_file:
for line in in_file:
out_file.write('{}\n'.format(len(line.split())))
Add newline in the file while writing
in_file = open("our_input.txt")
out_file =open("output.txt", "w")
for line in in_file:
line= (str(line)).split()
x=(len(line))
x=str(x)
out_file.write(x)
#Write newline
out_file.write('\n')
in_file.close()
As the previous answers have pointed out, your need to write a newline to separate the ouput.
Here is yet another way to write the code
with open("our_input.txt") as in_file, open("output.txt", "w") as out_file:
res = map(lambda line: len(line.split()), in_file)
for r in res:
out_file.write('%d\n' % r)

How to write lines from a input file to an output file in reversed order in python 3

What I want to do is take a series of lines from one text document, and put them in reverse in a second. For example text document a contains:
hi
there
people
So therefore I would want to write these same lines to text document b, except like this:
people
there
hi
So far I have:
def write_matching_lines(input_filename, output_filename):
infile = open(input_filename)
lines = infile.readlines()
outfile = open(output_filename, 'w')
for line in reversed(lines):
outfile.write(line.rstrip())
infile.close()
outfile.close()
but this only returns:
peopletherehi
in one line. any help would be appreciated.
One line will do:
open("out", "wb").writelines(reversed(open("in").readlines()))
You just need to + '\n' since .write does not do that for you, alternatively you can use
print >>f, line.rstrip()
equivalently in Python 3:
print(line.rstrip(), file=f)
which will add a new line for you. Or do something like this:
>>> with open('text.txt') as fin, open('out.txt', 'w') as fout:
fout.writelines(reversed([line.rstrip() + '\n' for line in fin]))
This code assumes that you don't know if the last line has a newline or not, if you know it does you can just use
fout.writelines(reversed(fin.readlines()))
Why do you rstrip() your line before writing it? You're stripping off the newline at the end of each line as you write it. And yet you then notice that you don't have any newlines. Simply remove the rstrip() in your write.
Less is more.
Update
If I couldn't prove/verify that the last line has a terminating newline, I'd personally be inclined to mess with the one line where it mattered, up front. E.g.
....
outfile = open(output_filename, 'w')
lines[-1] = lines[-1].rstrip() + '\n' # make sure last line has a newline
for line in reversed(lines):
outfile.write(line)
....
with open(your_filename) as h:
print ''.join(reversed(h.readlines()))
or, if you want to write it to other stream:
with open(your_filename_out, 'w') as h_out:
with open(your_filename_in) as h_in:
h_out.write(''.join(reversed(h_in.readlines()))

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