Python – How to check if a string is a substring of items in a list of strings

listpythonstring

I have a list:

my_list = ['abc-123', 'def-456', 'ghi-789', 'abc-456']

and want to search for items that contain the string 'abc'. How can I do that?

if 'abc' in my_list:

would check if 'abc' exists in the list but it is a part of 'abc-123' and 'abc-456', 'abc' does not exist on its own. So how can I get all items that contain 'abc'?

Best Answer

If you only want to check for the presence of abc in any string in the list, you could try

some_list = ['abc-123', 'def-456', 'ghi-789', 'abc-456']
if any("abc" in s for s in some_list):
    # whatever

If you really want to get all the items containing abc, use

matching = [s for s in some_list if "abc" in s]

Related Solutions

Python – How to check if a list is empty

if not a:
  print("List is empty")

Using the implicit booleanness of the empty list is quite pythonic.

Python – How to check whether a file exists without exceptions

If the reason you're checking is so you can do something like if file_exists: open_it(), it's safer to use a try around the attempt to open it. Checking and then opening risks the file being deleted or moved or something between when you check and when you try to open it.

If you're not planning to open the file immediately, you can use os.path.isfile

Return True if path is an existing regular file. This follows symbolic links, so both islink() and isfile() can be true for the same path.

import os.path
os.path.isfile(fname)

if you need to be sure it's a file.

Starting with Python 3.4, the pathlib module offers an object-oriented approach (backported to pathlib2 in Python 2.7):

from pathlib import Path

my_file = Path("/path/to/file")
if my_file.is_file():
    # file exists

To check a directory, do:

if my_file.is_dir():
    # directory exists

To check whether a Path object exists independently of whether is it a file or directory, use exists():

if my_file.exists():
    # path exists

You can also use resolve(strict=True) in a try block:

try:
    my_abs_path = my_file.resolve(strict=True)
except FileNotFoundError:
    # doesn't exist
else:
    # exists

Best Answer

Related Solutions

Python – How to check if a list is empty

Python – How to check whether a file exists without exceptions

Related Topic