Python section III

This time we learned to include tuples, dictionaries, and collections.

1. Tuple (tuple): Enclose with parentheses

   If there is only one element, add a comma behind it --tup=

   Tuples can be added

   (1,2,3)+(4,5,6)--(1,2,3,4,5,6)

   * indicates a few copies

   Convert tuples:tuple1=tuple (list)

   t= (' A ', ' B ', [' A ', ' B '])

   t[2][0]= ' X '

   t[2][1]= ' Y '

   t= (' A ', ' B ', [' X ', ' Y '])

   Tuples cannot be changed or deleted, but lists in tuples can be

3. Dictionary: Enclosed in curly braces

   Key-value pairs:

   D={key1:value1,key2:value2}

   Increase:

   By deleting:

   Change:

   Check:

   Keys (): list of all keys

   VALUES (): list of all values

   Items (): key values are

5. Set collection

   . Union for the set (123456)  set1| Set2

   . Intersection set1&set2

   . Difference

   . Symmetric_difference set1^set2

   Set1 (1,2,3,4)

   Set2 (3,4,5,6)

7. functions

   Strings,tuples,numbers immutable ( immutable )

   List, Set variable ( mutable "

   keyword parameter ( **xx

   default parameter: Default parameter must be placed on the last side

   indeterminate length parameter ( *xx tuple

9. Variable scope

   Global variables are scoped differently from local variables

   Different life cycle

   Global Variables declared with globals

   6. anonymous function:lambda[arg1[,arg2,..... argn]]:expression

   Sum=lambda a,b:a+b

Python section III