1. collection --------- set characteristics: ① collection type is set, not by way of access to the collection element group; ②: there is no repetition characteristics set
2. The basic operation of a set of several
①: the length of seeking support collections
②: Check whether an element in the collection inside
③: two sets of operation: Set differencing
④: the intersection of two sets of ------------- &
⑤: find the union of two sets: --------- |
⑥: how to define an empty set: ---------- the SET ()
3. Dictionary ------ dict type: a number of key and value, the type of collection (set), the sequence
4. dictionary related operations:
①: key visit by value, can not be accessed by way of a sequence of elements
②: If there are two identical can right-what will happen? Note: dictionary not have the same key, even if there will automatically delete one
③: value may be str int float set list dict ---------------- key but must be immutable type (int str)
Note: tuples can be a key but not when key list
④: empty dictionary, said:
to sum up:
Python basic data types:
A: Digital Number: int (integer) float (floating point) boolean (Boolean) complex (complex)
II: Group:
①: Sequence: string (str) list (list) tuple (tuple) ---------- subscript for the index to access, may slice a [1: 2]
②: collection: set disorder, there is no index, not sliced
③: Dictionary: dict key and value requirements
