循环列表不要删东西
lis = [11,22,33,44,55]
for i in range(len(lis)):
print(i)
del lis[i]
print(lis)
删除奇数位
第一种
lis = lis[::2]
print(lis)
第二种
l1 = []
for i in lis:
if lis.index(i) % 2 == 0:
l1.append(i)
lis = l1
print(lis)
l1 = []
l2 = l1
l3 = l1
l3.append('a')
print(l1,l2,l3)
循环字典不要删东西
删除键值中有K的键值对。
法一:
for i in dic:
if 'k' not in i:
dic1.setdefault(i,dic[i])
dic = dic1
print(dic)
法二:
l = []
for i in dic:
if 'k' in i:
l.append(i)
for i in l:
del dic[i]
print(dic)
元祖中若只有一个元素且不加逗号,那么元祖的类型就是此元素类型,不一定还是元祖。
tu1 = (1)
tu2 = (1,)
print(tu1,type(tu1))
print(tu2,type(tu2))
tu1 = ([1])
tu2 = ([1],)
print(tu1,type(tu1))
print(tu2,type(tu2))
# 转化成bool值都为错
# 0 '' [] () {} set()