I have a text file that will have the contents:
Line 1
,
,
Line 2
,
Line 3
,
Line 4
I would like to create a function that deletes the empty spaces between the lines (marked with , for illustration)
So far, I've created a function with the following code, but nothing happens when I run this:
with open('path/to/file.txt', 'r') as f:
for line in f:
line = line.strip()
Any help is appreciated.
If you want to remove blank lines from an existing file without writing to a new one, you can open the same file again in read-write mode (denoted by 'r+') for writing. Truncate the file at the write position after the writing is done:
with open('file.txt') as reader, open('file.txt', 'r+') as writer:
for line in reader:
if line.strip():
writer.write(line)
writer.truncate()
You need to override the file after changing:
with open('path/to/file.txt', 'r') as f:
new_text = '\n'.join([line.strip() for line in f.read().split('\n')] if line.strip())
with open('path/to/file.txt','w') as in_file:
in_file.write(new_text)
The line.strip() will only strip that line, but that does not mean that if the line is empty the line somehow will disappear. Furthermore you never really store the (processed) line in (another) file.
You can process the file and write the result to a target.txt file with:
with open('path/to/file.txt', 'r') as f:
with open('path/to/target.txt', 'w') as w:
for line in f:
if line.strip():
w.write(line)If you want to strip non-empty lines as well, so remove leading and trailing spaces from all lines, you can use the stripped variant:
with open('path/to/file.txt', 'r') as f:
with open('path/to/target.txt', 'w') as w:
for line in f:
line = line.strip()
if line:
w.write(line)
w.write('\n')This program will read the file line-by-line, which is often better for huge files, since loading a huge file in memory, can result in memory problems.
Furthermore it is often better to store the result in another file. If the machine crashes while processing (for example due to power failure), then you still have the original file. Most Linux commands are designed to write to another file. Such that later, when the operation is done, you move the target to the original file.
I would approach that like this:
with open('path/to/file.txt', 'r+') as f:
lines = f.readlines()
lines = [line.strip() for line in lines]
f.writelines(line)
You can remove the empty lines like this:
with open("txt.txt", "r") as f:
for l in f:
if l == "\n":
l = l.replace("\n", "")
with open("output.txt", "a") as f2:
f2.write(l)
If you want to remove blank lines from an existing file without writing to a new one, you can use random access instead. Open the file in read-write binary mode, keep track of the file's read position with the file.tell method as you read line by line, keep track of the file's write position when you write a non-blank line, restore the read and write positions when you read and write with the file.seek method, and finally, use the file.truncate method to truncate the file at the last write position:
write_position = 0
with open('file.txt', 'rb+') as f:
for line in f:
if line.strip():
read_position = f.tell()
f.seek(write_position)
f.write(line)
write_position = f.tell()
f.seek(read_position)
f.truncate(write_position)
Demo: https://repl.it/@blhsing/UncommonRevolvingTransversals
with open('path/to/file.txt', 'r') as f: #this opens the file in read mode
lines = [line for line in f.readlines() if line.strip() != ""] #this puts all the lines of the file into a nice list, but removes every line that is empty.
with open('path/to/file.txt', 'w') as f: #this just clears the contents
pass
for line in lines: #this goes through the lines list
with open('path/to/file.txt', 'a') as f: #this opens the file append mode
f.write(f'{line.strip()}\n') #this strips the line, and adds it at the end of the file and creates a new line
