Check if string ends with one of the strings from a list
Question:
What is the pythonic way of writing the following code?
extensions = ['.mp3','.avi']
file_name = 'test.mp3'
for extension in extensions:
if file_name.endswith(extension):
#do stuff
I have a vague memory that the explicit declaration of the for loop can be avoided and be written in the if condition. Is this true?
Answers:
Just use:
if file_name.endswith(tuple(extensions)):
Though not widely known, str.endswith also accepts a tuple. You don’t need to loop.
>>> 'test.mp3'.endswith(('.mp3', '.avi'))
True
I have this:
def has_extension(filename, extension):
ext = "." + extension
if filename.endswith(ext):
return True
else:
return False
There is two ways: regular expressions and string (str) methods.
String methods are usually faster ( ~2x ).
import re, timeit
p = re.compile('.*(.mp3|.avi)$', re.IGNORECASE)
file_name = 'test.mp3'
print(bool(t.match(file_name))
%timeit bool(t.match(file_name)
792 ns ± 1.83 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each)
file_name = 'test.mp3'
extensions = ('.mp3','.avi')
print(file_name.lower().endswith(extensions))
%timeit file_name.lower().endswith(extensions)
274 ns ± 4.22 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each)
I just came across this, while looking for something else.
I would recommend to go with the methods in the os package. This is because you can make it more general, compensating for any weird case.
You can do something like:
import os
the_file = 'aaaa/bbbb/ccc.ddd'
extensions_list = ['ddd', 'eee', 'fff']
if os.path.splitext(the_file)[-1] in extensions_list:
# Do your thing.
Another possibility could be to make use of IN statement:
extensions = ['.mp3','.avi']
file_name = 'test.mp3'
if "." in file_name and file_name[file_name.rindex("."):] in extensions:
print(True)
another way which can return the list of matching strings is
sample = "alexis has the control"
matched_strings = filter(sample.endswith, ["trol", "ol", "troll"])
print matched_strings
['trol', 'ol']
What is the pythonic way of writing the following code?
extensions = ['.mp3','.avi']
file_name = 'test.mp3'
for extension in extensions:
if file_name.endswith(extension):
#do stuff
I have a vague memory that the explicit declaration of the for loop can be avoided and be written in the if condition. Is this true?
Just use:
if file_name.endswith(tuple(extensions)):
Though not widely known, str.endswith also accepts a tuple. You don’t need to loop.
>>> 'test.mp3'.endswith(('.mp3', '.avi'))
True
I have this:
def has_extension(filename, extension):
ext = "." + extension
if filename.endswith(ext):
return True
else:
return False
There is two ways: regular expressions and string (str) methods.
String methods are usually faster ( ~2x ).
import re, timeit
p = re.compile('.*(.mp3|.avi)$', re.IGNORECASE)
file_name = 'test.mp3'
print(bool(t.match(file_name))
%timeit bool(t.match(file_name)
792 ns ± 1.83 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each)
file_name = 'test.mp3'
extensions = ('.mp3','.avi')
print(file_name.lower().endswith(extensions))
%timeit file_name.lower().endswith(extensions)
274 ns ± 4.22 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each)
I just came across this, while looking for something else.
I would recommend to go with the methods in the os package. This is because you can make it more general, compensating for any weird case.
You can do something like:
import os
the_file = 'aaaa/bbbb/ccc.ddd'
extensions_list = ['ddd', 'eee', 'fff']
if os.path.splitext(the_file)[-1] in extensions_list:
# Do your thing.
Another possibility could be to make use of IN statement:
extensions = ['.mp3','.avi']
file_name = 'test.mp3'
if "." in file_name and file_name[file_name.rindex("."):] in extensions:
print(True)
another way which can return the list of matching strings is
sample = "alexis has the control"
matched_strings = filter(sample.endswith, ["trol", "ol", "troll"])
print matched_strings
['trol', 'ol']