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
Modern browsers have Array#includes
, which does exactly that and is widely supported by everyone except IE:
console.log(['joe', 'jane', 'mary'].includes('jane')); //true
You can also use Array#indexOf
, which is less direct, but doesn't require polyfills for outdated browsers.
console.log(['joe', 'jane', 'mary'].indexOf('jane') >= 0); //true
Many frameworks also offer similar methods:
- jQuery:
$.inArray(value, array, [fromIndex])
- Underscore.js:
_.contains(array, value)
(also aliased as _.include
and _.includes
)
- Dojo Toolkit:
dojo.indexOf(array, value, [fromIndex, findLast])
- Prototype:
array.indexOf(value)
- MooTools:
array.indexOf(value)
- MochiKit:
findValue(array, value)
- MS Ajax:
array.indexOf(value)
- Ext:
Ext.Array.contains(array, value)
- Lodash:
_.includes(array, value, [from])
(is _.contains
prior 4.0.0)
- Ramda:
R.includes(value, array)
Notice that some frameworks implement this as a function, while others add the function to the array prototype.
Best Answer
numpy.savetxt
saves an array to a text file.