综合练习：词频统计

str_context=‘‘‘There are several reasons for this. To begin with, 
nowadays college students aim too high. All they want are “good” 
jobs which could offer good salary, comfortable working conditions, high social status among others. Consequently,
 most college students are unwilling to accept vacant jobs they consider not “good” enough.
  Another reason is that there is a big gap between the majors some students study in school and the demands of vacant jobs.
 So companies think some students are not fit for the jobs.‘‘‘

a = str_context.replace(‘’‘,‘ ‘).lower().split()
b = str_context.split()

str = {}
for i in b:
    count = a.count(i)
    str[i] = count

word = ‘‘‘the are is i in i‘m if what why where and my a to at‘‘‘
c = word.split()
for i in c:
    if i in str.keys():
        del (str[i])

count = sorted(str.items(),key=lambda items: items[1], reverse=True)

for i in range(10):
    print(count[i])