Simple usage of built-in functions in Python

Python provides an inline module buildin, which defines some functions frequently used in software development. These functions can be used to achieve data type conversion, data calculation, sequence processing, etc.

Built-in functions of the buildin module:
1. apply(): You can call a function with a variable parameter list and store the parameters in a tuple or sequence. apply The tuple parameters must be consistent with the parameters of sum()

#!/usr/bin/python
# -*- coding:utf8 -*-
def sum(x=1,y=2):
  return x+y
print apply(sum,(1,3))

2. filter():You can filter a certain sequence. The filtered func() parameter cannot be empty.
filter(func or None, sequence) –>list, tuple, or string

#!/usr/bin/python
# -*- coding:utf8 -*-
def func(x):
  if x>0:
    return x
print filter(func,range(-9,10))

3. reduce(): Continuous operations on elements in the sequence can be processed through loops and have the function of continuous processing.

reduce(func,sequence[,initial]) –> value

func is a custom function. Func() implements continuous operations on the parameter sequence. sequence is the sequence to be processed. If the parameter
The value of initial is not empty. The function func() will be first passed in for calculation. If it is empty, the value of initial will be processed.

#!/usr/bin/python
# -*- coding:utf8 -*-
def sum(x,y):
    return x + y
print reduce(sum,range(0,10))
print range(0,10)
print reduce(sum,range(0,10),10)
print reduce(sum,range(0,2),10)

4. map(): You can perform the same operation on each element of multiple sequences and return it as a list.
If multiple sequences are provided, the elements in each sequence will be calculated in one-to-one correspondence; if the length of each sequence is different,
add "None" after the short sequence and then calculate

map(func,sequence[,sequence,…]) –> list

#!/usr/bin/python
# -*- coding:utf8 -*-
def power(x):
  return x**x
print map(power,range(1,5))

def power2(x,y):
  return x**y
print map(power2,range(1,5),range(5,1,-1))
print range(1,5)
print range(5,1,-1)

PS: Commonly used built-in module functions:
abs(x)                                                                                                                                                                                                                                                          [,kwargs]])                                                                                                           out out out outgoing Return False
cmp(x,y) Compare the size of x,y The value of the formula
float(x) Convert numbers or strings into float type data
hash(object) Return the hash value of an object
help([object]) Return the help description of the inline function
id(x) Returns the identifier of an object
input([prompt]) Accepts input from the console and converts the input value into a number
int(x) Converts a number or string to an integer
len(obj) The number of elements contained in the object
range([start,]end[,step]) Produce a list and return
raw_input([prompt]) Accept input from the console and return String type
reduce(func,sequence[,initial])                                                                                                                                                                                                                                                                                      .
sorted(iterable[,cmp[,key[,reverse]]]) Returns a sorted list
sum(iterable[,start=0]) Returns the sum of a sequence
type(obj) Return the type of an object. The elements of the list return




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