Python Learning notes Section Fourth

Collection and review

Remove an element from a list in a list

Remove (Element) brackets fill an element instead of an index

Take value

Traverse the list of songs by index

Do not traverse by index
Common actions for lists:

Comparison

Meta-group

Dictionary Common operations:

Adding elements from a list within a tuple

Avoid errors in dictionary values

Traversing elements in a dictionary

Convert a dictionary key to a list

Dictionary values are converted to lists and values (dictionaries are unordered)

Calculation of list elements

Calculate the calculation of key in the dictionary, with a separate volues do not use all

It's worth counting in the dictionary

Dictionary SetDefault not added, there is no matter

Create dictionary Mode 1

Create Dictionary Mode 2

Create dictionary Mode 3

Update overwrite some overrides, no add, original unchanged

New Dictionary Element

Delete a dictionary element

Popitem Random Deletion

Result is 2
The inclusion of a dictionary

The Judgment list is empty

Boolean value calculation

Numeric positive negative number decimal is true 0,none, NULL is False

Determines whether the input is empty

CMD comes with a Boolean value, if the input is not empty, that is true, input null is wrong
Not is to take the inverse
If not cmd if CMD is not true then continue
It's true, keep the print down.
And then continue the loop.

Collection of Loops

Relational operations for collections
Take the common part

Takes all the elements of a set, and adds two sets

There is only one in the collection, minus the same

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Subtraction

Intersection

and set

Symmetric difference Sets

Overwrite S2 to S1

Increase

Delete, no error

Delete, will error

Delete, random

Subsets and Super

Judgment, no intersection returns TRUE, there is a return false

Python Learning notes Section Fourth