python學習記錄三
阿新 • • 發佈:2017-07-26
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:
#讀 f = open("yesterday","r",encoding="utf-8") data = f.read() f.close() #寫 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