Programmer's Python Data - Sequences
Written by Mike James   
Monday, 11 December 2023
Article Index
Programmer's Python Data - Sequences
Modifying Sequences

Modifying Sequences

No, it’s not a paradox or a contradiction. The tuple is immutable and you can’t change it after it is defined, but the need to modify a tuple, and other immutable sequences, is a common one. This sometimes worries beginners, but changing immutable data is very easy – you simply create a new data object with the desired elements. For example, if you want to delete the ith element of a tuple you would use

u = t[:i]+t[i+1:]

You can see that u is a new tuple built by concatenating two slices of t. Clearly t is still immutable, but if you write:

t = t[:i]+t[i+1:]

it does look as if t has been changed. What has happened, of course, is that t is set to reference the new tuple and the original tuple that t references will be garbage collected as long as there is no other variable referencing it.

Similarly if you want to add an element to a tuple you can use:

t = t[:i]+(42,)+t[i+1:]

where in this case you need to use a trailing comma to create a tuple with one element.

In general, to manipulate a tuple, or any immutable data structure, you simply take the data apart and then put it back together to create a new data structure, see String Manipulation in the next chapter for more examples.

In chapter but not in this extract

  • Tuples
  • Modifying Immutable Sequences
  • Destructuring
  • Sorting & Order
  • Ranges



  • A sequence isn’t like a data type encountered in other languages. It is more a mixin that can be added to or found in a range of different data types.

  • The archetypal sequence is the list, closely followed by the tuple.

  • All sequences can be indexed and sliced.

  • Indexing selects a particular element of the sequence and if it doesn’t exist throws an exception.

  • Slicing extracts or modifies a subsequence and never throws an exception.

  • Sequences also support a range of useful methods including in which can test to see if an object is part of a sequence.

  • A tuple is an immutable list.

  • Even though a tuple is immutable it can appear to be modified by creating new tuples derived from existing tuples.

  • A sequence is always an iterable

  • Destructuring can be used to access the elements in a list, tuple or, in general, any iterable.

  • Being able to sort its element is specific to lists and tuples.

  • The range sequence is a functional implementation of a sequence and is useful whenever you need to create an integer sequence.

Programmer's Python
Everything is Data

Is now available as a print book: Amazon


  1. Python – A Lightning Tour
  2. The Basic Data Type – Numbers
       Extract: Bignum
  3. Truthy & Falsey
  4. Dates & Times
  5. Sequences, Lists & Tuples
       Extract Sequences 
  6. Strings
       Extract Unicode Strings
  7. Regular Expressions
  8. The Dictionary
       Extract The Dictionary 
  9. Iterables, Sets & Generators
       Extract  Iterables 
  10. Comprehensions
       Extract  Comprehensions 
  11. Data Structures & Collections
  12. Bits & Bit Manipulation
         Extract Bits and BigNum ***NEW!!!
  13. Bytes
        Extract Bytes And Strings
        Extract Byte Manipulation 
  14. Binary Files
  15. Text Files
  16. Creating Custom Data Classes
        Extract A Custom Data Class 
  17. Python and Native Code
        Extract   Native Code
    Appendix I Python in Visual Studio Code
    Appendix II C Programming Using Visual Studio Code





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Arrays in Python

Advanced Python Arrays - Introducing NumPy

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Last Updated ( Monday, 11 December 2023 )