Python Learning notes-built-in data structures

1, List--is a sequence, for sequential storage of data

Definition and initialization of a list

In [374]: LST = list () in [375]: lstout[375]: []in [376]: LST = []in [377]: LST = [1,2,3]in [378]: lstout[378]: [1, 2, 3]in [379]: LST = list (range (1,10)) in [380]: lstout[380]: [1, 2, 3, 4, 5, 6, 7, 8, 9]

Accessing list elements

in [380]: lstout[380]: [1, 2, 3, 4,  5, 6, 7, 8, 9]in [381]: in [381]: in [381]: lst[0]out[ 381]: 1in [382]: lst[-1]out[382]: 9in [383]: lst.index (5) Out[383]: 4In  [384]: in [384]: lst = [1,2,3,2,4,3,5]in [385]: lst.index (2)   The    # index  method returns the first index found Out[385]: 1in [386]: lst.index (2,2) out[386]:  3in [387]: lst.index (2,2,5) out[387]: 3in [388]: lst.index (2,-4,-1) Out[388]:  3in [389]: lst.count (2) Out[389]: 2in [390]: lst.count (3) Out[390]: 2 

• Accessing elements by index

• The index method returns the first index based on a value

• The Count method returns the number of elements in the list

Modification of list elements

In [391]: lstout[391]: [1, 2, 3, 2, 4, 3, 5]in [392]: lst[2]out[392]: 3In [393]: lst[2] = 5In [394]: lstout[394]: [1, 2, 5 , 2, 4, 3, 5]in [395]: lst[2] out[395]: 5

Increase of list elements

in [396]: lstout[396]: [1, 2, 5, 2, 4, 3, 5]in [397]:  Lst.append (in [398]: lstout[398]: [1, 2, 5, 2, 4, 3, 5, ) 19]in [399]: lst.insert (0,20) in [400]: lstout[400]: [20, 1, 2, 5,  2, 4, 3, 5, 19]in [401]: lst.insert ( -1, ' B ') in [402]: lstout[402] : [20, 1, 2, 5, 2, 4, 3, 5,  ' B ', 19]in [403]:  Lst.insert (+, ' a ') in [404]: lstout[404]: [20, 1, 2, 5, 2, 4, 3,  5,  ' B ', 19,  ' A ']in [405]: lst.insert ( -100, ' a ') in [406]: lstout[406]:  [' A ', 20, 1, 2, 5, 2, 4, 3, 5,  ' B ', 19,  ' a ']In  [407]:  #insert   When an index is out of range, the index is negative   It is inserted before the No. 0 element, the index is positive   It is inserted after the last element in [407]:  Lst.extend ([i]) in [408]:  lstout[408]: [' A ', 20, 1, 2, 5, 2, 4, 3, 5,  ' B ',  19,  ' A ',  1, 2, 3] #append操作单个元素, extend operations iterate objects

Deletion of list elements

In [410]: lstout[410]: [1, 2, 3, 2, 4, 3, 5, 3, 4]in [411]: Lst.remove (1) in [412]: lstout[412]: [2, 3, 2, 4, 3, 5, 3, 4]in [413]: Lst.pop () out[413]: 4In [414]: lstout[414]: [2, 3, 2, 4, 3, 5, 3]in [415]: Lst.pop (4) out[415]: 3In [416]: lstout[41 6]: [2, 3, 2, 4, 5, 3]in [417]: Lst.clear () in [418]: lstout[418]: []

Other operations

In [419]: lst = list (Range (4)) in [420]: lstout[420]: [0, 1, 2,  3]in [421]: len (LST) out[421]: 4in [422]: in [422]: lstout[422]:  [0, 1, 2, 3] In [423]: lst.reverse () in [424]: lstout[424]: [3, 2, 1, 0]in [425 ]: in [425]: lst.sort () in [426]: lstout[426]: [0, 1, 2, 3]in  [427]: lst.sort (reverse=true) in [428]: lstout[428]: [3, 2, 1, 0]in  [429]: in [429]: lstout[429]: [3, 2, 1, 0]in [430]: lst2  = LSTIN [431]: LST2OUT[431]: [3, 2, 1, 0]IN [432]: LST2[1]  = 5 In [433]: lst2Out[433]: [3, 5, 1, 0]In [434]:  Lstout[434]: [3, 5, 1, 0]in [435]: in [435]: lst2 = lst.copy ()In [436]: lst2out[436]: [3, 5, 1, 0]in [437]: lstout[437]: [3,  5, 1, 0]in [438]: lst2[1] = 7in [439]: lst2out[439]: [3,  7, 1, 0]IN [440]: LSTOUT[440]: [3, 5, 1, 0]

2, meta-group

Definition and initialization

In [441]: t = tuple () in [442]: T out[442]: () in [443]: T = () in [444]: T-out[444]: () in [445]: T = (all in all) in [446]: tout[4 ": (1, 2, 3) in [447]: t = tuple (range (3)) in [448]: tout[448]: (0, 1, 2) tuples are immutable

Inquire

In [449]: T-out[449]: (0, 1, 2) in []: t[0]out[450]: 0In [451]: t[-1]out[451]: 2In [452]: T.index (2) out[452]: 2In [453]: T.count (2) out[453]: 1

Named tuples

In [454]: From collections import Namedtuplein [455]: User1 = namedtuple (' A ', [' name ', ' age ']) in [456]: me = User (' Martin ', 1 8) in [457]: meout[457]: A (name= ' Martin ', age=18) in [458]: me.ageout[458]: 18In [459]: me.nameout[459]: ' Martin ' in [460]: M E[0]OUT[460]: ' Martin ' in [461]: me[1]out[461]: 18

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Python Learning notes-built-in data structures