What are the similarities and differences between Python lists, tuples, and dictionaries
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List: []
Features: modifiable
Basic operations:
Index []
Slice []
Append append
Delete del
Length len
Include in
Eg:
> name_list = ('hello','jacky','dick')
> delname_list [0]
Traceback (mostrecent call last):
File "", line 1, in
TypeError:'tuple' object doesn't support item deletion
> type (name_list)
> name_list = ['jacky','dick','hello']
> id (name_list)
35733128L
> name_list.append ('hu')
> name_list
['jacky',' dick','hello', 'hu']
> id (name_list)
35733128L
> delname_list [0]
> name_list
['dick',' hello','hu']
How to turn a list into a string:
> "_" .join (name_list)
'dick_hello_hu'
> len (name_list)
three
> name_list
['dick',' hello','hu']
> > "jacky" in name_list
False
Tuple: ()
Features: unmodifiable
Basic operations:
Index []
Slice []
Length len
Include in
['dick','hello',' hu'] list
('dick',' hello','hu') tuple
[
'dick', ('jacky','kirk')
]
The list contains two elements:
First: string
Second: tuple
Add, delete and modify: minimum unit
# slice, index (- 1), length, contain, loop
Str: re-open up memory space
List: use the original memory space after modification
Tuple: modification is not allowed
Name_list = ['liu','zhang','huang']
For ele in name_list
Print ele
# 1 minute ele = liu
# 2 dint ele = zhang
# 3 minute ele = huang
If ele = 'zhang':
Print 'sb'
# this cycle will not continue
Continue
If ele = 'liu':
Print 'find'
Break
# jump out of the whole cycle
# for
# continue
# break
While condition:
Print 'xxx'
Condition = true true: loop
Condition = false false: no loop
While True:
Print 'xxxx'
Flag = True
While flag:
Print 'jjjj'
Flag = False
Print 'vvvv'
Dict, dictionary, key-value pair
Person = {
"name": 'dick'
"age": 18
"gender": 'man'
}
# each element is a key-value pair (key and value)
The dictionary can also be found through the "index", corresponding to the keys of the dictionary:
Person ['name']
Dict_test.py:
Person = {
"name": "dick"
"age": 29
"gerder": 'man'
}
# person.keys () # all key are taken out and saved as a list
# person.values () # all value are taken out and saved as a list
# person.items () # all elements # all key-value pairs
For KJO v in person.items ():
Print k
Print v
Print'='
Execution result:
E:\ > pythondict_test.py
Gender
Man
=
Age
twenty-nine
=
Name
Dick
=
Dictionary disorder, special for loop
Keys ()-- > list
Values ()-- > list
Items ()-- > when only the for loop is used, the element is assigned
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