17 Tips for Beginners in Python

Swap Variables

x = 6

y = 5

X, y = y, X

Print X

>>> 5

Print Y

>>> 6

　　If statement in row

Print "Hello" if True else "world"

>>> Hello

　　Connection

The last way to do this is to be cool when binding two different types of objects.

NFC = ["Packers", "49ers"]

AFC = ["Ravens", "patriots"]

Print NFC + AFC

>>> [' Packers ', ' 49ers ', ' Ravens ', ' patriots ']

Print str (1) + "World"

>>> 1 World

print ' 1 ' + "world"

>>> 1 World

Print 1, "World"

>>> 1 World

Print NFC, 1

>>> [' Packers ', ' 49ers '] 1

　　Calculation techniques

#向下取整

Print 5.0//2

>>> 2

# 2 of the 5-time Square

Print 2**5

>> 32

　　Note the division of floating-point numbers

Print. 3/.1

>>> 2.9999999999999996

Print. 3//.1

>>> 2.0

　　Numerical comparison

x = 2

If 3 > x > 1:

Print X

>>> 2

If 1 < x > 0:

Print X

>>> 2

　　Two simultaneous iteration of lists

NFC = ["Packers", "49ers"]

AFC = ["Ravens", "patriots"]

For TeamA, teamb in Zip (NFC, AFC):

Print TeamA + "vs." + Teamb

>>> Packers vs. Ravens

>>> 49ers vs. Patriots

　　List Iteration with index

Teams = ["Packers", "49ers", "Ravens", "patriots"]

For index, team in enumerate (teams):

Print index, Team

>>> 0 Packers

>>> 1 49ers

>>> 2 Ravens

>>> 3 Patriots

　　List derivation

A list of known, brush to select even list method:

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

even = []

For number in numbers:

If number%2 = = 0:

Even.append (number)

Replace it with the following

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

even = [number for number in numbers if number%2 = = 0]

• Dictionary derivation

Teams = ["Packers", "49ers", "Ravens", "patriots"]

Print {Key:value for value, key in enumerate (teams)}

>>> {' 49ers ': 1, ' Ravens ': 2, ' Patriots ': 3, ' Packers ': 0}

　　Initialize the value of the list

Items = [0]*3

Print items

>>> [0,0,0]

　Convert a list to a string

Teams = ["Packers", "49ers", "Ravens", "patriots"]

Print ",". Join (teams)

>>> ' Packers, 49ers, Ravens, Patriots '

　　Get elements from a dictionary

Do not use the following methods

data = {' user ': 1, ' name ': ' Max ', ' Three ': 4}

Try

Is_admin = data[' admin ']

Except Keyerror:

Is_admin = False

Replaced by

data = {' user ': 1, ' name ': ' Max ', ' Three ': 4}

Is_admin = data.get (' admin ', False)

　　Get child list

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

#前3个

Print X[:3]

>>> [About]

#中间4个

Print X[1:5]

>>> [2,3,4,5]

#最后3个

Print X[-3:]

>>> [4,5,6]

#奇数项

Print X[::2]

>>> [1,3,5]

#偶数项

Print X[1::2]

>>> [2,4,6]

　　60 Character Resolution Fizzbuzz

A short time ago Jeff Atwood promoted a simple programming exercise called Fizzbuzz, which referred to the following questions:

Write a program that prints the number 1 to 100, 3 multiples print "Fizz" to replace this number, 5 multiples print "Buzz", for a number that is both a multiples of 3 and a multiples of 5 to print "Fizzbuzz".

Here is a short way to solve this problem:

For x in range (101):p rint "Fizz" [x%3*4::]+ "Buzz" [X%5*4::]or X

　Collection

Use the Counter library.

From collections Import Counter

Print Counter ("Hello")

>>> Counter ({' L ': 2, ' h ': 1, ' E ': 1, ' O ': 1})

　　Iterative Tools

Like the collections library, there's a library called Itertools.

From Itertools import combinations

Teams = ["Packers", "49ers", "Ravens", "patriots"]

For-game in combinations (teams, 2):

Print game

>>> (' Packers ', ' 49ers ')

>>> (' Packers ', ' Ravens ')

>>> (' Packers ', ' patriots ')

>>> (' 49ers ', ' Ravens ')

>>> (' 49ers ', ' patriots ')

>>> (' Ravens ', ' patriots ')

　　False = = True

In Python, true and false are global variables, so:

False = True

If False:

Print "Hello"

Else

Print "World"

>>> Hello

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17 Tips for Beginners in Python