Python Learning lists and dictionaries

List

Basic Operations
>>>len ([1,3,4])
3

>>>[1,2,3]+[4,5,6] + number must be of the same type
[1,2,3,4,5,6]

>>>[' ni! '] *
[' ni! ', ' ni! ', ' ni! ', ' ni! ']

>>>STR ([up]) + "34"
' [1,2]34 '

>>>[1,2]+list ("34")
[1,2,3,4]


list Iteration and parsing
>>>3 in [+]
True

>>>for x in [£ º]
Print (x,end= ");
The
>>> res = [C-for-C in ' spam '];
>>>res
[' SSSs ', ' pppp ', ' aaaa ', ' mmmm ']

index shards and matrices

>>>l = [' AA ', ' BB ', ' CC ']
>>>L[2]
' CC '
>>>l[-2]
' BB '
>>>l[1:]
[' BB ', ' CC ']


lists are mutable, they support the manipulation of the list object in place

index vs. Shard Assignment

>>>l = [' AA ', ' BB ', ' CC ']
>>>l[1]= ' DD '
>>>l
[' AA ', ' DD ', ' CC ']

>>>l[0:2]=[' xx ', ' yy ']
>>>l
[' xx ', ' yy ', ' CC ']

invocation of a list method

>>>l.append (' AA ')
>>>l
[' xx ', ' yy ', ' cc ', ' AA ']
>>>l.sort ()
>>>l
[' AA ', ' cc ', ' xx ', ' yy ']
>>>l.sort (key=str.lower) sorted by lowercase in string
[' AA ', ' cc ', ' xx ', ' yy ']

>>>l.sort (Key=str.lower,reverse = True) flip
>>>l
[' yy ', ' xx ', ' cc ', ' AA ']


>>>l = [up]
>>>l.extend ([3,4,5]) extension
>>>l
[1,2,3,4,5]

>>>l.pop () launch last element
>>>l
[1,2,3,4]

>>>l.reverse () Flip
>>>l
[4,3,2,1]


>>>l = []
>>>l.append (1) Add data
>>>l.append (2)
>>>l
[Up]

>>>l = [' AA ', ' BB ', ' CC ']
>>>l.index (' AA ') index
0

>>>l.insert (1, ' xx ') insert
>>>l
[' AA ', ' xx ', ' BB ', ' CC ']


>>>l.remove (' xx ') removal
>>>l
[' AA ', ' BB ', ' CC ']

>>>l.pop (1) removing an indexed element
>>>l
[' AA ', ' CC ']



Other common list operations

>>>l = [' AA ', ' BB ', ' CC ']
>>>del l[0] Delete list element
>>>l
[' BB ', ' CC ']

>>>del l[1:] Delete list shards
>>>l
[' AA ']

>>>l = [' AA ', ' BB ', ' CC ']
>>>l[1:] = [] Delete list shards
>>>l
[' AA ']




Dictionary

In addition to the list, the dictionary is perhaps the most flexible data structure in Python.
basic operation of the dictionary

>>>d = {' spam ': 2, ' Ham ': 1, ' Eggs ': 3}
>>>d[' spam '] value via key
2

>>>d
{' spam ': 2, ' Ham ': 1, ' Eggs ': 3}

>>>len (d) Length
3
>>> ' Ham ' in D members
True

>>>list (D.keys ()) converts the dictionary key to list
[' Eggs ', ' ham ', ' spam ']


Modify dictionary in situ

>>>d[' ham '] = [' Grill ', ' bake ', ' fry '] assignment
>>>d
{' spam ': 2, ' Ham ': [' grill ', ' bake ', ' fry '], ' Eggs ': 3}

>>>del d[' eggs '] Delete
>>>d
{' spam ': 2, ' Ham ': [' grill ', ' bake ', ' fry ']}

Other Dictionary methods
>>>d = {' spam ': 2, ' Ham ': 1, ' Eggs ': 3}
>>>list (D.values ())
[3,1,2]


>>>list (D.items ())
[(' Eggs ', 3), (' Ham ', 1), (' Spam ', 2)]

>>>d.get (' spam ')
2

>>>print (D.get (' toast '))
None

>>>d.get (' Toast ', 88) default value
88

the Update method of the dictionary is similar to merging the same overlay
>>>d2 = {' Toast ': 4, ' Muffin ': 5, ' Eggs ': 3}
>>>d.update (D2)
>>>d
{' spam ': 2, ' Ham ': 1, ' eggs ': 5, ' toast ': 4, ' Muffin ': 5}

>>>d.pop (' Muffin ')
{' spam ': 2, ' Ham ': 1, ' eggs ': 5, ' Toast ': 4}

Python Learning lists and dictionaries