集合
a=[1,2,3,4,5,5,6,6,6,7]
b=set(a) #去掉重复的元素
print(b,type(b))
c=(1,1,2,2,2,3,3,4,4,5)
d=set(c)
print(d,type(d))
e='12342435653'
f=set(e)
print(f,type(f))
g={}
print(g,type(g))
打印:
a={1,2,3}
for d in a:
print(d)
集合基本操作:
sets=set((1,2,3,4,5))
print(sets)
集合元素的增删改查:
a=set('123')
print(a)
a.add('acd') #添加元素
print(a)
a.update('abd') #添加集合
print(a)
b=a.pop() #随机删除集合里的一个元素,并返回删的元素
print(b)
a={1,2,3,4,5,5,6,6}
a.remove(3)
#a.remove(0) #删除一个没有的元素时会报错
print(a)
a.discard(4)
a.discard(9) #删除一个没有的元素时不会报错,提示None
b=a.discard(9)
print(b)
print(a)
集合之间的操作:
a={1,2,3,4,5}
b={4,5,6}
d={1,2,3}
c=a.union(b) #联合
print(a)
print(b)
print(c)
c=a.intersection(b) #交集
print(c)
c=a.difference(b) #a不同于b
print(c)
c=b.difference(a) #b不同于a
print(c)
c=a.symmetric_difference(b)
print(c)
print(a.issuperset(d)) #父集,a包含d,d在a集合里,a是b的父集
print(a.issuperset(b))
print(d.issubset(a)) #子集,a包含d,d在a集合里,b是a的子集
print(a.issubset(d))
print(a.isdisjoint(b)) #判断是不是没有交集,没有的话输出true,有就是false
print(b.isdisjoint(d))
c=a-b
print(c) #同c=a.difference(b)
c=a|b
print(c) #同c=a.union(b)
c=a&b #同c=a.intersection(b)
print(c)
print(3 in a)
print(a==b)
print(a!=b)
打印0-999
a=[i for i in range(1000)]
print(a)
输出1000以内的偶数
a=[i for i in range(0,1000,2)]
print(a)
或
a=[i for i in range(1000) if i%2==0]
print(a)
输出200-500把3和5同时整除的数
a=[i for i in range(200,501) if i%5==0 and i%7==0]
print(a)
输出示例:
a=[[1,2,3],[4,5,6],[7,8,9]]
b=[a[i][1] for i in range(len(a))] #输出258
print(b)
c=[a[i][2] for i in range(len(a))] #输出369
print(c)
d=[a[i][i] for i in range(len(a))] #输出159
print(d)
e=[a[i][i] for i in range(len(a)-1,-1,-1)] #输出951
print(e)
f=[a[i][-i+2] for i in range(len(a))] #输出357 f=a[[i][-i-1] for i in range(len(a))]
print(f)
a=[[3*j+1+i for i in range(3)] for j in range(3)] #输出[[1, 2, 3], [4, 5, 6], [7, 8, 9]]
print(a)
a=[[4*j+1+i for i in range(4)] for j in range(4)] #输出[[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12], [13, 14, 15, 16]]
print(a)
交换key,value值
a={1:20,3:40,5:60}
b={v:k for k,v in a.items()} #字符反转
print(b)
示例:
a={'a':30,'b':4,'A':20,'B':22,'c':21}
b={k.lower():(a.get(k.lower(),0)+a.get(k.upper(),0)) for k in a.keys()}
print(b)
循环打印元素:
例1
a='123'
for i in a:
print(i)
例2:
a=['123',3,5,6,(3,4,5)]
for i in a:
print(i)
例3:
for i in range(2,7,3):
print(i)
例4:打印出下标和对应元素
a='asdfghhjjkk'
for xb,i in enumerate(a):
print(xb,i)
输出:
a={'name':'张三','age':'34','add':'China'}
#输出键
for k in a: #in a,默认是a.keys
print(k)
#输出键
for k in a.keys():
print(k)
#输出值
for v in a.values():
print(v)
#输出键值对
for k,v in a.items():
print(k,v)
统计每个元素出现的次数:
a=[1,1,2,2,2,3,3,3,3,3,4,6,6,7,8]
for i in set(a):
print('%d出现的次数为:'%i,a.count(i))