Pythont特殊语法filter,map,reduce,apply使用方法

add = lambda x,y : x + y
print add(1,2)

sequence = [1,2,3,4,5,6,7,8,9,10]
fun = lambda x : x % 2 == 0
seq = filter(fun,sequence)
print seq

def filter(fun,seq):
    filter_seq = []
    for item in seq:
        if fun(item):
            filter_seq.append(item)
    return filter_seq

seq = [1,2,3,4,5,6]
fun = lambda x : x << 2

print map(fun,seq)

def map(fun,seq):
    mapped_seq = []
    for item in seq:
        mapped_seq.append(fun(item))
    return mapped_seq

seq = [1,2,3,4,5,6,7,8,9,10]
fun = lambda x,y: x + y

print reduce(fun,seq,0)

def reduce(fun,seq,initVal = None):
    Lseq = list(seq)
    if initVal is None:
        res = Lseq.pop(0)
    else:
        res = initVal
    for item in Lseq:
        res = fun(seq,item)
    return res

def say(a,b):
    print a,b

apply(say,(234,'Hello World!'))