␡
- 5.1 Introduction
- 5.2 Lists
- 5.3 Tuples
- 5.4 Unpacking Sequences
- 5.5 Sequence Slicing
- 5.6 del Statement
- 5.7 Passing Lists to Functions
- 5.8 Sorting Lists
- 5.9 Searching Sequences
- 5.10 Other List Methods
- 5.11 Simulating Stacks with Lists
- 5.12 List Comprehensions
- 5.13 Generator Expressions
- 5.14 Filter, Map and Reduce
- 5.15 Other Sequence Processing Functions
- 5.16 Two-Dimensional Lists
- 5.17 Intro to Data Science: Simulation and Static Visualizations
- 5.18 Wrap-Up
This chapter is from the book
This chapter is from the book
This chapter is from the book
This chapter is from the book
5.6 del Statement
The del statement also can be used to remove elements from a list and to delete variables from the interactive session. You can remove the element at any valid index or the element(s) from any valid slice.
Deleting the Element at a Specific List Index
Let’s create a list, then use del to remove its last element:
In [1]: numbers = list(range(0, 10)) In [2]: numbers Out[2]: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] In [3]: del numbers[-1] In [4]: numbers Out[4]: [0, 1, 2, 3, 4, 5, 6, 7, 8]
Deleting a Slice from a List
The following deletes the list’s first two elements:
In [5]: del numbers[0:2] In [6]: numbers Out[6]: [2, 3, 4, 5, 6, 7, 8]
The following uses a step in the slice to delete every other element from the entire list:
In [7]: del numbers[::2] In [8]: numbers Out[8]: [3, 5, 7]
Deleting a Slice Representing the Entire List
The following code deletes all of the list’s elements:
In [9]: del numbers[:] In [10]: numbers Out[10]: []
Deleting a Variable from the Current Session
The del statement can delete any variable. Let’s delete numbers from the interactive session, then attempt to display the variable’s value, causing a NameError:
In [11]: del numbers In [12]: numbers ------------------------------------------------------------------------- NameError Traceback (most recent call last) <ipython-input-12-426f8401232b> in <module>() ----> 1 numbers NameError: name 'numbers' is not defined