python provides many built-in functions to learn about these internal functions can be called directly when the built-in function in some cases just need to implement function when not required to write additional code, such as: selecting the maximum value directly max (), etc.
1, abs () absolute value
1 a=-99 2 print(abs(a))
2, help () View help view function modules use or detailed description for the parameters in parentheses class object
. 1 Help ( ' STR ' ) # See methods which string 2 . 3 A = [l, 2,3 ] . 4 Help (a.append) # view of a particular method of use
3, dir () Returns the attributes of the parameters, the list method, the object may be a parameter, variable, type
1 by aa = [1,2,3 ] 2 Print ( the dir ( by aa))
4, max () min () maximum and minimum values
. 1 AA = [2,55,344,22,33,55,66 ] 2 Print (max (AA)) # maximum . 3 Print (min (AA)) # Min
5, chr (), ord () number to String, String to digital (only a single character)
1 bb=89 2 print(chr(bb)) 3 4 print(ord('a'))
6, sorted function operation on all sorts of objects iterations
1 dict1 = {'name':'python','age':'20','address':'sz'} 2 print(sorted(dict1.items(),key=lambda item:item[0]))
7, map () function is provided to do according to the specified sequence mapping, map actually is an iterator
map(function, iterable, ...)
function - Function
iterable - one or more sequences
1 def fun(a): 2 return a**2 3 4 list1 = [1,2,3,4,5,6] 5 print(list(map(fun,list1)))
8, filter () for filtering a sequence filter out ineligible element returns an iterator object
. 1 DEF fun1 (A): 2 IF A> 10 : . 3 return A . 4 . 5 list3 = [1,3,33,1,22,0,99 ] . 6 Print (List (filter (fun1, list3))) # Filter out of 10 less than the number
9, isinstance () determines whether an object of a type known
. 1 str1 = ' A ' 2 Print (the isinstance (str1, STR)) # result is True . 3 Print (the isinstance (str1, int)) # result is False