String slices

Github logo Edit on GitHub
  • A segment of a string is called a slice. Selecting a slice is similar to selecting a character:
>>> s = 'Monty Python'
>>> s[0:5]
'Monty'
>>> s[6:12]
'Python'

-The operator [n:m] returns the part of the string from the “n-eth” character to the “m-eth” character, including the first but excluding the last.

  • If you omit the first index (before the colon), the slice starts at the beginning of the string.
>>> fruit = 'banana'
>>> fruit[:3]
'ban'
  • If you omit the second index, the slice goes to the end of the string:
>>> fruit[3:]
'ana'
  • If the first index is greater than or equal to the second the result is an empty string, represented by two quotation marks:
>>> fruit = 'banana'
>>> fruit[3:3]
''
  • By default, Python sets this increment to 1, but that extra colon at the end of the numbers allows us to specify the slicing increment.
>>>s=”karpagam”
>>>s[::2]
kraa
  • It also possible to apply negative index.
>>>s=”karpagam”
>>>s[-3:-1]
ga
Previous
String Operations
Next
Immutable String

References

  • Allen B. Downey, “Think Python: How to Think Like a Computer Scientist‘‘, 2nd edition, Updated for Python 3, Shroff/O‘Reilly Publishers, 2016 (http://greenteapress.com/wp/thinkpython/)
  • Guido van Rossum and Fred L. Drake Jr, ―An Introduction to Python – Revised and updated for Python 3.2, Network Theory Ltd., 2011.
  • John V Guttag, ―Introduction to Computation and Programming Using Python‘‘, Revised and expanded Edition, MIT Press , 2013
  • Robert Sedgewick, Kevin Wayne, Robert Dondero, ―Introduction to Programming in Python: An Inter-disciplinary Approach, Pearson India Education Services Pvt. Ltd., 2016.
  • Timothy A. Budd, ―Exploring Python‖, Mc-Graw Hill Education (India) Private Ltd.,, 2015. 4. Kenneth A. Lambert, ―Fundamentals of Python: First Programs‖, CENGAGE Learning, 2012.
  • Charles Dierbach, ―Introduction to Computer Science using Python: A Computational Problem-Solving Focus, Wiley India Edition, 2013.
  • Paul Gries, Jennifer Campbell and Jason Montojo, ―Practical Programming: An Introduction to Computer Science using Python 3‖, Second edition, Pragmatic Programmers, LLC, 2013.