17 Tips for Beginners in Python

Swap variables

x = 6y = 5x, y = y, xprint x>>> 5print 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 worldprint ' 1 ' + "World" >>> 1 worldprint 1, "World" >>> 1 WORLDP Rint NFC, 1>>> [' Packers ', ' 49ers '] 1

Calculation techniques

#向下取整print 5.0//2>>> 2 5-time print 2**5>> 32

Note the division of floating-point numbers

Print .3/.1>>> 2.9999999999999996print .3//.1>>> 2.0

Numerical comparison

x = 2if 3 > x > 1:   print x>>> 2if 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)}>>> {' 49er S ': 1, ' Ravens ': 2, ' Patriots ': 3, ' Packers ': 0}

Initialize the value of the list

Items = [0]*3print 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]>>> [x-ray] #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 Counterprint 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 combinationsteams = ["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 = Trueif false:   print "Hello" else:   print "World" >>> Hello

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