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python學習記錄三

pri data open 對稱 位置 sleep col pytho --

一、集合:

list_1 = [1,4,5,7,3,6,7,9]
list_1 = set(list_1)

list_2 = set([2,6,0,66,22,8,4])

#交集
list_1.intersection(list_2) #list_1 & list_2

#並集
list_1.union(list_2) #list_1 | list_2

#差集
list_1.difference(list_2) #list_1 - list_2
list_2.difference(list_1) #list_2 - list_1

list_3 = set([1,3,7])
#子集
list_3.issubset(list_1) #list_3 <= list_1 #父集 list_1.issuperset(list_3) #list_1 >= list_3 #對稱差集 list_1.symmetric_difference(list_2) #list_1 ^ list_2 list_4 = set([5,6,8]) list_3.isdisjoint(list_4) #沒有交集返回Ture list_1.add(999) #添加 list_1.update([888,777,555]) list_1.remove(4) #刪除
list_1.discard(‘ddd‘)
len(list_1) #取長

二、文件:

#
f = open("yesterday","r",encoding="utf-8")
data = f.read()
f.close()

#
f = open("yesterday2","w",encoding="utf-8")
f.write("我愛北京天安門\n")
f.write("天安門上太陽升")
f.close()

#讀前5行
f = open("yesterday","r",encoding="utf-8")
for i in range(5):
    line = f.readline()
f.close()

#
讀每一行 f = open("yesterday","r",encoding="utf-8") for index,line in enumerate(f.readlines()): if index == 9: print(---------------------------) continue print(line.strip()) #高效率讀 for line in f: print(line) f.close() f = open("yesterday","r",encoding="utf-8") print(f.tell()) f.read(5) print(f.tell()) #打印光標位置 f.seek(0) #光標移到開始位置 f.close() import sys,time for i in range(20): sys.stdout.write(#) sys.stdout.flush() time.sleep(0.2)

三、函數

#遞歸
def calc(n):
    print(n)
    if int(n/2)>0:
        return calc(int(n/2))
    print("->",n)

calc(10)

#高階函數
def add (a,b,f):
    return f(a)+f(b)

res = add(3,-6,abs)
print(res)

python學習記錄三