10 minutes a day, 12 days Getting Started Python (four)

map()The function receives two parameters, one is a function, the other is a sequence, map Functions the passed-in function sequentially to each element of the sequence and returns the result as a new list.

defNum(x):
ReturnX*X

PrintMap(num,[1,2,3,4,5,6,7,8,9])

# [1, 4, 9, +, A, $, +,--]

reduce()A function that acts on a sequence [X1, x2, x3 ...] , the function must receive two parameters, and reduce calculates the result and the next element of the sequence, and the effect is:

def add (x, y) :
   return x+ y

print reduce (Add,[1 , 3 , 5 , 7 , 9 ])

#25

defList2num(x, Y):
ReturnX*Ten+Y

PrintReduce(list2num,[1,3,5,7,9])

#13579

sorted()The function can sort the list:

PrintSorted([3,6,8,9,4,1,2])
#[1, 2, 3, 4, 6, 8, 9]

defreversed_cmp(x, Y):
IfX>Y:
Return-1
Else:
Return1
return0

PrintSorted([3,6,8,9,4,1,2],REVERSED_CMP)
# [9, 8, 6, 4, 3, 2, 1]

The python closures are similar to those in javascript:

defLazy_sum(*Args:
defs():
Returnsum([x forXinchArgs])
returnS

F= Lazy_sum (1,2,3,4,5)

PrintF ()
# 15
F2= Lazy_sum ()

PrintF2 ()
# 0

Implementing anonymous functions via lambda:

F = lambda x: x*x

print F (5)
# 25

10 minutes a day, 12 days Getting Started Python (four)