When reading lines from a text file using python, the end-line character often needs to be truncated before processing the text, as in the following example:
f = open("myFile.txt", "r")
for line in f:
line = line[:-1]
# do something with line
Is there an elegant way or idiom for retrieving text lines without the end-line character?
This question is related to
python
Long time ago, there was Dear, clean, old, BASIC code that could run on 16 kb core machines: like that:
if (not open(1,"file.txt")) error "Could not open 'file.txt' for reading"
while(not eof(1))
line input #1 a$
print a$
wend
close
Now, to read a file line by line, with far better hardware and software (Python), we must reinvent the wheel:
def line_input (file):
for line in file:
if line[-1] == '\n':
yield line[:-1]
else:
yield line
f = open("myFile.txt", "r")
for line_input(f):
# do something with line
I am induced to think that something has gone the wrong way somewhere...
Simple. Use splitlines()
L = open("myFile.txt", "r").read().splitlines();
for line in L:
process(line) # this 'line' will not have '\n' character at the end
What do you thing about this approach?
with open(filename) as data:
datalines = (line.rstrip('\r\n') for line in data)
for line in datalines:
...do something awesome...
Generator expression avoids loading whole file into memory and with ensures closing the file
What's wrong with your code? I find it to be quite elegant and simple. The only problem is that if the file doesn't end in a newline, the last line returned won't have a '\n' as the last character, and therefore doing line = line[:-1] would incorrectly strip off the last character of the line.
The most elegant way to solve this problem would be to define a generator which took the lines of the file and removed the last character from each line only if that character is a newline:
def strip_trailing_newlines(file):
for line in file:
if line[-1] == '\n':
yield line[:-1]
else:
yield line
f = open("myFile.txt", "r")
for line in strip_trailing_newlines(f):
# do something with line
You may also consider using line.rstrip() to remove the whitespaces at the end of your line.
What's wrong with your code? I find it to be quite elegant and simple. The only problem is that if the file doesn't end in a newline, the last line returned won't have a '\n' as the last character, and therefore doing line = line[:-1] would incorrectly strip off the last character of the line.
The most elegant way to solve this problem would be to define a generator which took the lines of the file and removed the last character from each line only if that character is a newline:
def strip_trailing_newlines(file):
for line in file:
if line[-1] == '\n':
yield line[:-1]
else:
yield line
f = open("myFile.txt", "r")
for line in strip_trailing_newlines(f):
# do something with line
You may also consider using line.rstrip() to remove the whitespaces at the end of your line.
What's wrong with your code? I find it to be quite elegant and simple. The only problem is that if the file doesn't end in a newline, the last line returned won't have a '\n' as the last character, and therefore doing line = line[:-1] would incorrectly strip off the last character of the line.
The most elegant way to solve this problem would be to define a generator which took the lines of the file and removed the last character from each line only if that character is a newline:
def strip_trailing_newlines(file):
for line in file:
if line[-1] == '\n':
yield line[:-1]
else:
yield line
f = open("myFile.txt", "r")
for line in strip_trailing_newlines(f):
# do something with line
Simple. Use splitlines()
L = open("myFile.txt", "r").read().splitlines();
for line in L:
process(line) # this 'line' will not have '\n' character at the end
You may also consider using line.rstrip() to remove the whitespaces at the end of your line.
Simple. Use splitlines()
L = open("myFile.txt", "r").read().splitlines();
for line in L:
process(line) # this 'line' will not have '\n' character at the end
Long time ago, there was Dear, clean, old, BASIC code that could run on 16 kb core machines: like that:
if (not open(1,"file.txt")) error "Could not open 'file.txt' for reading"
while(not eof(1))
line input #1 a$
print a$
wend
close
Now, to read a file line by line, with far better hardware and software (Python), we must reinvent the wheel:
def line_input (file):
for line in file:
if line[-1] == '\n':
yield line[:-1]
else:
yield line
f = open("myFile.txt", "r")
for line_input(f):
# do something with line
I am induced to think that something has gone the wrong way somewhere...
Simple. Use splitlines()
L = open("myFile.txt", "r").read().splitlines();
for line in L:
process(line) # this 'line' will not have '\n' character at the end
What do you thing about this approach?
with open(filename) as data:
datalines = (line.rstrip('\r\n') for line in data)
for line in datalines:
...do something awesome...
Generator expression avoids loading whole file into memory and with ensures closing the file
Source: Stackoverflow.com