python 笔记

python判断变量是否为数字

>>> a = "03523"
>>> a.isdigit()
True
>>> b = "963spam"
>>> b.isdigit()
False

 

 
https://www.decalage.info/en/python/print_list
key 在dict 判断

if 'key1' in dict:
  print "blah"
else:
  print "boo"

python 文件读写
file = open(“testfile.txt”,”w”) 
 file.write(“Hello World”) 


Convert a List Into a Set 
fruit = [ banana, orange, pineapple ]
set(fruit)

>>> a = set(["Blah", "Hello"])
>>> a = list(a) # You probably wrote a = list(a()) here or list = set() above
>>> a
['Blah', 'Hello']

set 遍历

weekdays = set(['MON', 'TUE', 'WED', 'THU', 'FRI', 'SAT', 'SUN'])
 
for d in weekdays:
    print (d)

isset

# 判断是否在dict中 
d = {}
d["a"] = 11
d["b"] = 22
if "a" in d :
    print "sss"
sst = set([2,3,4] )

# 遍历set 
for e in sst :
    print e 
# 判断是否在set     
if 20 in sst:
    print"20 in sst "
else:
    print " 20 not in sst"