What is the easiest way to get all strings that do not start with a character?
Solution 1
Use generator expressions, the best way I think.
for line in (line for line in x if not line.startswith('?')):
DO_STUFF
Or your way:
for line in x:
if line.startswith("?"):
continue
DO_STUFF
Or:
for line in x:
if not line.startswith("?"):
DO_STUFF
It is really up to your programming style. I prefer the first one, but maybe second one seems simplier. But I don't really like third one because of a lot of indentation.
Solution 2
Here is a nice one-liner, which is very close to natural language.
String definition:
StringList = [ '__one', '__two', 'three', 'four' ]
Code which performs the deed:
BetterStringList = [ p for p in StringList if not(p.startswith('__'))]
Solution 3
Something like this is probably what you're after:
with open('myfile.txt') as fh:
for line in fh:
if line[0] != '?': # strings can be accessed like lists - they're immutable sequences.
continue
# All of the processing here when lines don't start with question marks.
drbunsen
Updated on August 25, 2020Comments
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drbunsen over 3 years
I am trying to parse about 20 million lines from a text file and am looking for a way to do some further manipulations on lines that do not start with question marks. I would like a solution that does not use regex matching. What I would like to do is something like this:
for line in x: header = line.startswith('?') if line.startswith() != header: DO SOME STUFF HERE
I realize the
startswith
method takes one argument, but is there any simple solution to get all lines from a line that DO NOT start with a question mark? Thanks in advance for the help. -
drbunsen almost 13 yearsThank you very much for the help!