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An example analysis of basic data types and their common usage in Python. In order to solve this problem, this article introduces the corresponding analysis and solution in detail, hoping to help more partners who want to solve this problem to find a more simple and feasible method.

List

First of all, List is included by []. Each element is separated by (comma). Any data type can be nested in List, and data types can be nested with each other (except set), such as:

# define a list

Li = ['name':, 1, True, (' baked, 'caged,), [1,2,3], {' salted fish'}, {1,2}]

# ergodic

For i in li:

# print data types and values

Print (type (I), I)

The value of the list

# define a list

Li = ['name':, 1, True, (' baked, 'caged,), [1,2,3], {' salted fish'}, {1,2}]

# take the value through the index. Note that the index starts from 0.

Temp1 = li [0]

Print (temp1) # a

# list values are nested in the list

Temp2 = li [4] [0]

Print (temp2) # 1

# remember string slicing? List can do the same, but the value is still a list.

Temp3 = li [1:5:]

Print (temp3) # [1, True, ('baked,' c'), [1, 2, 3]]

List modification

# remember mutable types and immutable types? Variable means that the value of an element can be changed.

Li = ['await,' baked,'c']

Li [0] ='b'

Print (li)

# change the value of part of the index with slicing

Li [0:2] = ['clockjobo']

Print (li)

# error demonstration: immutable data types cannot change the value of an index

Str1 = 'abc'

Print (str1 [0]) # can print the value of an index

Str1 [0] ='1' # changing the value of an index throws an exception TypeError: 'str' object does not support item assignment

List deletion

Li = ['await,' baked,'c']

# Delete an element according to the index

Del li [0]

Print (li)

# Delete the element of an index and return the deleted value. Delete the last element by default

Li = ['await,' baked,'c']

Temp1 = li.pop () # assign the returned deleted value to a variable and print it.

Print (li)

Print (temp1)

Temp2 = li.pop (0) # you can also pass in the index to be deleted

Print (li)

Print (temp2)

# Delete the value by value and delete one from the leftmost

Li = [11,'22, 22, 33, 44, 22]

Li.remove (22)

Print (li)

Li = ['await,' baked,'c']

# clear the entire list

Li.clear ()

Print (li)

List insertion

# add a value to the specified index location

Li = [1,2,3,4,5,6]

Li.insert (2, 'lll') # insert (index location, value to add)

Print (li)

# append to the object

Li = [1,2,3,4,5,6]

Li.append ("aaa") # appends a single element

Li.append ([11,22,33]) # appended list as an element

Print (li)

# expand the list

Li = [1,2,3,4,5,6]

Li.extend ("aaa") # adds each element of the string to the original list

Li.extend ([11,22,33]) # add each element of the list to the original list

Print (li)

# merge two lists

Li1 = [1, 2, 3, 4]

Li2 = ['averse,' baked, 'crested,' d']

Li3 = li1+li2

Print (li3)

List query

# determine whether a value exists in the list and return a Bool value

Li = [1, 2, 3, 4]

Res = 2 in li

Print (res)

# determine how many times a value exists in the list

Li = [1,2,2,3,2,4]

Res = li.count (2)

Print (res)

# determine that a value is in the index of the list. There are multiple indexes that return the first value

Li = [1, 2, 3, 4]

Res = li.index (2)

Print (res)

# if there is no exception thrown

# li = [1, 2, 3, 4]

# res = li.index (6)

# print (res) # ValueError: 6 is not in list

List reversal

Li = [1,'a', 2,'b']

Li.reverse ()

Print (li)

List sort, maximum (minimum) valu

# Note that only data of the same type can be sorted. Take the maximum and minimum values, and you cannot mix numbers with strings.

Li = [8,2,6,8,5]

Li.sort () # sort

Print (li) li = ['baked,' 5percent, 'zonal,' yearly, 'ringing,' l']

Li.sort ()

Print (li)

# maximum

Print (max (li))

# minimum

Print (min (li))

Conversion between list and string

# convert string to list

Str1 = 'abcdefg'

Li = list (str1)

Print (li)

# convert a list to a string. Note that the list can only be full of strings

Li = ['1miles,' asides, 'canals,' 2']

S1 ='. Join (li)

Print (S1)

# the list contains numeric type

Li = [1,2, 'asides,' b']

# define an empty string first

S1 =''

# iterate through the list

For i in li:

# convert a numeric type to a string concatenated to an empty string defined earlier

S1 + = str (I)

Print (S1)

Tuple

Tuples are immutable, values cannot be changed according to the index, cannot be added and deleted, and tuples are included with (), such as:

Tu = (111,22,33,), [(1,2,3)], 222,333, True,)

Tuples can also be indexed, sliced, and traversed. It will not be demonstrated here.

There are two ways:

Count (a) # gets the number of specified elements that appear in the tuple

Index (a _) # gets the index of the specified element in the tuple

A little knowledge:

Tuples are also parentheses, and the method looks the same. In order to make it easier to distinguish and more intuitive, we usually add an extra comma after it, which is a good specification. For example:

Tu = (1, 2, 3,)

Dictionaries

The dictionary uses {} to include key-value pairs composed of key and value. The dictionary is an unordered collection list, and the dictionary cannot be used as a key value. The key value can only be unique. Other data types can still be nested in the dictionary, such as:

Dic = {

'K1':'v1'

'K2girls: 'v2'

'k3':'v3'

'K2percent: 'v4'

False: "aa"

0: "bb"

'k4legs: [1, 2, 3, 4]

'k5legs: {

'K1':'v1'

}

}

Print (dic)

Take a value

Dic = {

'K1':'v1'

'K2girls: 'v2'

'k3':'v3'

'K2percent: 'v4'

False: "aa"

0: "bb"

'k4legs: [1, 2, 3, 4]

'k5legs: {

'K1': 'v11'

}

}

# the dictionary is valued through key, and the list in the dictionary is still valued through the index

Print (dic ['K5'] [' K1']) # v11

Print (dic ['k4'] [0]) # 1

Print (dic ['kkkk']) # key that does not exist throws an exception KeyError

# it is recommended to use get,key to return value for existence, but not to return the second parameter.

Print (dic.get ('kkkk')) # returns None without throwing an exception (default)

Print (dic.get ('kkkk',' does not exist')) # returns' does not exist'at this time

Ergodic

Dic = {

'K1':'v1'

'K2girls: 'v2'

'k3':'v3'

'K2percent: 'v4'

False: "aa"

0: "bb"

'k4legs: [1, 2, 3, 4]

'k5legs: {

'K1': 'v11'

}

}

# in the dictionary, key is the same as the last overlay, and the front True is 1 False is 0. It can be observed that only false,value in the key is overwritten 'bb'' later.

# the default cycle is the key value

Print ('one:')

For i in dic:

Print (I)

# the default cycle is the key value

Print ('two:')

For i in dic.keys ():

Print (I)

# the loop is the value value

Print ('three:')

For i in dic.values ():

Print (I)

# Loop key and value

Print ('four:')

For iMagazine j in dic.items ():

Print (iMagnej)

Fromkeys

# use the first parameter as the key value and the second parameter as the unified value to generate a dictionary

Dic0 = dict.fromkeys ('a') # the second parameter does not write value defaults to None, null value, which is not equal to empty string ('')

Print (dic0)

Dic1 = dict.fromkeys ('averse,' b')

Print (dic1)

Dic2 = dict.fromkeys ('asides, [1, 2, 3]) # the second parameter generates a dictionary as a unified value

Print (dic2)

Dic3 = dict.fromkeys (['axiaqingjiaomiao baozhongjingc'], [1min2prr3])

Print (dic3)

Add

Dic = {

'K1':'v1'

'K2girls: 'v2'

'k3':'v3'

}

# key that already exists will modify the value of the corresponding key, and key that does not have will add the corresponding value

Dic ['k4'] =' v4'

Print (dic)

# key that already exists returns the corresponding value. If not, add key and value.

V1 = dic.setdefault ('K1N1,' v111')

Print (dic, v1)

V2 = dic.setdefault ('k123regions,' v123')

Print (dic, v2)

Modify

Dic = {

'K1':'v1'

'K2girls: 'v2'

'k3':'v3'

'k4century: 'v4'

'k5times: 'v5'

}

# overwrite the previous value by using the unique feature of key

Dic ['K1'] =' v111'

Print (dic)

# update (input data in dictionary form)

Dic.update ({'K2Qing:' v222'})

Print (dic)

# Update multiple

Dic.update ({'k3pm:' v33319', 'v333')

Print (dic)

# you can also write key=value directly

Dic.update (k5cm / k555')

Print (dic)

# updating a key that does not exist is equivalent to adding

Dic.update (k6pm / k666')

Print (dic)

Delete

# delete and get the value pop (parameter 1, parameter 2)

Res = dic.pop ('K1')

Print (dic,res)

# throw an exception if you delete a key that does not exist without passing in the second parameter

# res = dic.pop ('k111')

# print (dic,res) # KeyError

Res = dic.pop ('k111fujinghee key does not exist')

Print (dic,res) # returns the second parameter

# Delete the last pair of keys and values in the dictionary and return them

KBI v = dic.popitem ()

Print (dic,k,v)

# clear the dictionary

Dic.clear ()

Print (dic) on the basic data types in Python and their commonly used sample analysis questions are shared here, I hope the above content can be of some help to you, if you still have a lot of doubts to be solved, you can follow the industry information channel for more related knowledge.

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