The del command is one way to remove an entry by referencing a specific key. To add several entries, it is more efficient to use a dict method called update. This example shows the syntax for adding a single entry by invoking a new key. The copyright of the book belongs to Elsevier. This notebook contains an excerpt from the Python Programming and Numerical Methods - A Guide for Engineers and Scientists, the content is also available at Berkeley Python Numerical Methods.
#Basic data structures in python update
update ( bdexamp ) #add several new entries print ( adexamp ) del adexamp print ( adexamp ) Variables and Basic Data Structures Python Numerical Methods. Left and right squirrely brackets are used to assign sets. Duplicates values are not possible within a set. Sets can be used to perform typical set operations such as union, intersection, set differences, and so on. Sets are another immutable data type that holds a unique collection of objects. We will see other uses when we encounter dictionaries. One obvious use for tuples for holding data that must be write-protected. However, because of the immutability of c, attempting to modify an element with an instruction such as c = 99will result in an error. The output after running this code looks almost exactly like a list. Notice that we can put any object we please into the tuple defined as the variable c. The syntax for forming a tuple uses parentheses (instead of square brackets for forming a list): a =Ĭ =( 4, 9, a, b, 'zxcv' ) print ( c ) print ( type ( c ))
Everything that you have learned so far about indexing and slicing also applies to tuples.
Similar to strings, they cannot be changed once they have been assigned. This section introduces two more immutable data types useful for holding collections of objects: tuples and sets. Recall that lists are mutable while strings are immutable. We have introduced the concepts of mutable and immutable objects in Python. Explore Python data structures and delve into the details of some of the basic structures, such as linked lists, stacks, and queues.
0 kommentar(er)
