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Python: len() function

len() function

The len() function is used to get the length of an object.

Version:

(Python 3.2.5)

Syntax:

len(s)

Parameter:

Name Description Required /
Optional
s A sequence (string, bytes, tuple, list, or range) or a collection (dictionary, set or frozen set). Required

Return value:

The number of items of an object.

Example: Python len() function 

ExampleList = []
print(ExampleList, 'length is', len(ExampleList))

Output:

[] length is 0

Pictorial Presentation:

Python: Built-in-function - len() function

Example: Python len() function with List

ExampleList = [2, 4, 6]
print(ExampleList, 'length is', len(ExampleList))

Output:

[2, 4, 6] length is 3

Pictorial Presentation:

Python: Built-in-function - len() function

Example: Python len() with Tuple


ExampleTuple = (2, 4, 6)
print(ExampleTuple, 'length is', len(ExampleTuple))

Output:

(2, 4, 6) length is 3

Example: Python len() with Range


ExampleRange = range(3, 12)
print('Length of', ExampleRange, 'is', len(ExampleRange))

Output:

Length of range(3, 12) is 9

Python Code Editor:

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Python: Tips of the Day

Find current directory and file's directory:

To get the full path to the directory a Python file is contained in, write this in that file:

import os 
dir_path = os.path.dirname(os.path.realpath(__file__))

(Note that the incantation above won't work if you've already used os.chdir() to change your current working directory, since the value of the __file__ constant is relative to the current working directory and is not changed by an os.chdir() call.)

To get the current working directory use

import os
cwd = os.getcwd()

Documentation references for the modules, constants and functions used above:

  • The os and os.path modules.
  • The __file__ constant
  • os.path.realpath(path) (returns "the canonical path of the specified filename, eliminating any symbolic links encountered in the path")
  • os.path.dirname(path) (returns "the directory name of pathname path")
  • os.getcwd() (returns "a string representing the current working directory")
  • os.chdir(path) ("change the current working directory to path")

Ref: https://bit.ly/3fy0R6m