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2025-01-19 Update From: SLTechnology News&Howtos shulou NAV: SLTechnology News&Howtos > Development >
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This article mainly explains "what are the basic data types of Python". The content of the explanation is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "what are the basic data types of Python"?
1. Numerical value
Int
Flaot
two。 String String
Get length
Three ways of string concatenation
String slicing
Specify character lookup
Character count
3. Boolean boolean
True
Flase
4. Null None
5.list list
Elements can be of different types, ordered collections.
6. Tuple tuple
The element cannot be changed after being defined
7. Dictionary dictionary
Store the key value and find it very quickly.
8. Set sets
Disordered and unrepeated sequence
9. Use a Mini Program to illustrate the format specification of python.
One: numerical value
There are only two types of values in Python
1.int
2.float
Defining values is very convenient and reduces a lot of definitions, such as the definition of axi3 in c
Int a = 3 Spacer c
A = 3#python
Python will automatically identify your number as int or float, so it is slower than the c language.
A = 3.14#float
Constants are defined in uppercase, such as PI=3.14, and in other languages, constants are immutable. They can be changed in python due to loss of qualification, but try not to change them.
> PI=3.14
> PI
3.14
> PI = PI+2
> PI
5.140000000000001
**
Two: string
**
Definition of string
Direct assignment is used to define strings in python. Strings can be enclosed in single quotation marks, double quotation marks and three quotation marks.
> sworn roomabc'
> > s
'abc'
> s= "abcd"
> > s
'abcd'
> slotted girls, please abdcboys
> > s
'abdc'
> len (s) # len () get length
four
There are three ways to concatenate strings:
1JI + number splicing
> s = 'abc'+'bcd'
> > s
'abcbcd'
> S1 = sworn roomabc'
> > S1
'abcbcdabc'
2.list ordered set concatenation (using the + sign to concatenate a large number of characters requires a lot of code)
> list_str = ['ni','hao','bei','jin']
> str2 = '.join (list_str)
> str2
'nihaobeijin'
>
> str3
'ni hao bei jin'
3.format concatenation: use {} to empty the strings that need to be stitched, followed by stitching
> str3 ='I like {} because I need {} '.format (' python',' efficient')
> str3
"I like python because I need to be efficient."
The slicing of the string: (start: end: interval), do not write from the beginning and the end by default. You can also use split cutting:
> s = 'abcdefgh'
> > s [0:3]
> s [: 3] starts from 0 by default
'abc'
> > s [3:]
'defgh'
> > s [:-1]
'abcdefg'
> > s [:-2]
'abcdef'
> s = 'abcdegh'
> s [:: 2] / / start, end, interval
'aceh'
> a = 'abcdef'
> a [::-1] / / can be used for string inversion
'fedcba'
> str4 = "Xiao Hong, Xiao Bai, Xiao Hua"
Str4.split (",")
['Xiao Hong, Xiao Bai, Xiao Hua']
String lookup:
> s = 'abcdefgh'
> str2.find ('a')
0
# cannot find and return-1
> s = 'abc'
> s.find ('d')
-1
String subscript query:
> s = 'abcdefgh'
> str2.index ('b')
one
String count:
> str3 = 'aaabbbccc'
> str3.count ('b')
three
Three: Boolean
Contains only two values, True and False. (clearly case sensitive)
> > 3 > > 3 > 2
True
> 3 > 2 and 3 > > 3 > 2 or 3 > not 3 > false
False
Four: None value
Represents an empty type
> s = None
> > s
> type (s) # use type () to view parameter types
Five: list list
The elements in list are unrestricted # and are ordered collections, so you can get the
Classmates = ['yh','xiaobai','xiaohong']
> type (classmates)
> len (classmates)
three
> classmates [0]
'yh'
> classmates [- 1]
'xiaohong'
List added, directly added in the last bit
Classmates.append ('')
Classmates
['yh',' xiaobai', 'xiaohong',' ']
Insert, you can specify the location to insert
> classmates.insert
> classmates
['yh',' hehe', 'xiaobai',' xiaohong', '']
Pop-up element, the default is the last bit, or you can specify a location
> > classmates.pop ()
''
Classmates.pop (3)
'xiaohong'
> classmates
['yh',' hehe', 'xiaobai']
The element in list can be a list
> s = ['python','java', [123123],' hehe']
> > len (s)
four
Six: tuple
Once the definition of the # element cannot be changed, the reference can be modified.
> t = (1pm 2pm 3)
> > t
(1, 2, 3)
> t [1]
two
> t = ('1pm, 2pm, 3')
> > t
('1','2','3')
Elements cannot be modified after they are defined
> t = ('1pm, 2pm, 3')
> > t
('1','2','3')
> l = [1BI 2]
> > t [2] = l
Traceback (most recent call last):
File "", line 1, in
TypeError: 'tuple' object does not support item assignment
> > t [2] = 3
Traceback (most recent call last):
File "", line 1, in
TypeError: 'tuple' object does not support item assignment
But the reference can be modified, that is, it can be modified when the element in the tuple is a reference.
> l = [1pc2jp3] Zhengzhou abortion price http://www.zzzykdfk.com/
> t = (1pm 2pm l)
> l = [3, 2, 2, 1]
> > t
(1, 2, [1,2,3])
> t [2] [0] = 3ram / represents the first element in the third element l of t.
> > t
(1,2, [3,2,3])
Seven: dictionary
A collection of dictionnary unordered objects, mapped through key-value. Marked with "{}", the search speed is extremely fast, just find the key value. It takes up a lot of memory (storing not only values, but also key values). Key uses immutable objects and uses key to calculate the location, usually using the hash algorithm.
> names = ['yh','','hehe']
>
> d = {'yh':90,'xiaohong':20,'hehe':70}
> d ['hehe']
seventy
> d ['xiaogou'] = 3 words added, out of order.
> > d
{'yh': 90,' xiaohong': 20, 'hehe': 70,' xiaogou': 30}
Find out if it exists
> 'hehe' in d
True
> 123 in d
False
> d.get ('123century maxim 1) # if not found, return-1. Check a certain value without looking for it first, which will report an error. Searching first can prevent it from reporting an error.
-1
> d.pop ('xiaogou')
sixty
> > d
{'yh': 90,' xiaohong': 20, 'hehe': 70}
Eight: gather sets
A sequence of unordered, non-repeating elements, often used to remove duplicates, intersections, and unions. Very fast
> s = set ([1, 1, 3, 3, 4, 4])
> > s
{1, 3, 4}
> > s.add (3)
> > s
{1, 3, 4}
> s.add (2)
> > s
{1, 2, 3, 4}
> S1 = set ([1pm 2p3])
> S2 = set ([2pm 3pr 4])
S1 & S2
{2, 3}
> > S1 | S2
{1, 2, 3, 4}
Nine: hail conjecture
Arbitrarily write a positive integer N and transform it according to the following rules:
If it is an odd number, the next step becomes 3N+1.
If it is an even number, the next step is to change to NUnip 2.
Will eventually become 1.
Code:
Def collatz (number): # def is a function of python, usually starting with "def function name (argument):"
The if number%2 = = 0 if # function is formatted with four spaces, that is, a tab key, followed by the following:
The statement tab after return number//2#if
Elif number%2 = = 1:#elif is the same, that is
Return 3*number+1
Print ('Please inter a number:') # print enter an integer on the screen
Try:# error check. If the input is not a positive integer, an error will be reported.
Num = int (input ())
If the content is true, it will do this loop all the time. This number is not equal to 1, then it will always operate on this number.
Print (collatz (num))
Num = collatz (num)
Except ValueError:#, this is the error message.
Print ('you must input an int number')
Thank you for your reading, the above is the content of "what are the basic data types of Python". After the study of this article, I believe you have a deeper understanding of what the basic data types of Python have, and the specific use needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!
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