Python anonymous functions lambda and switch implementation, pythonlambda

Python anonymous functions lambda and switch implementation, pythonlambda

1. lambda syntax is similar to es6 arrow Function

>>> show=lambda x,y: x * y>>> show( 10, 20 )200

2. Recursive factorial

>>> def fab( n ):...     if n == 0:...             return 1...     else:...             return n * fab( n - 1)... >>> fab( 3 )6>>> fab( 5 )120>>> fab( 6 )720>>> 

Using the reduce function, you can also perform a cumulative operation.

>>> l = range( 1, 6 )>>> l[1, 2, 3, 4, 5]>>> def f( x, y ):...     return x * y... >>> reduce( f, l )120>>> 

You can use lambda expressions to simplify the definition of functions.

>>> fab = lambda x, y: x * y>>> reduce( fab, [ 1, 2, 3, 4, 5, 6 ] )720>>> reduce( lambda x,y: x *y, [ 1, 2, 3, 4, 5, 6 ] )720>>> 

3. The dictionary + function can be used to determine the switch branch.

If .... Else implements addition and subtraction

#!/usr/bin/python#coding:utf-8from __future__ import divisiondef add( a, b ):    return a + bdef sbb( a, b ):    return a - bdef mul( a, b ):    return a * bdef div( a, b ):    return a / bdef oper( x, o, y ):    if o == '+':        return add( x, y )    elif o == '-':        return sbb( x, y )    elif o == '*':        return mul( x, y )    elif o == '/':        return div( x, y )    else:        passprint oper( 10, '/', 20 )

Transform a dictionary and a function into a switch

#! /Usr/bin/python # coding: utf-8from _ future _ import divisiondef add (a, B): return a + bdef sbb (a, B ): return a-bdef mul (a, B): return a * bdef div (a, B): return a/boper = {'+': add, '-': sbb, '*': mul, '/': div} def mySwitch (o, x, y): # return outputs [o] (x, y) # outputs. get (o) is equivalent to using [0] to retrieve a return Token in the dictionary. get (o) (x, y) print mySwitch ('/', 10, 20)