How to solve dictionary changed size during iteration error?

Question

I want pop out all the large values and its keys in a dictionary, and keep the smallest. Here is the part of my program

for key,value in dictionary.items():
         


        

Answer 1

Here is one way to solve it:

1. From the dictionary, get a list of keys, sorted by value
2. Since the first key in this list has the smallest value, you can do what you want with it.

Here is a sample:

# A list of grades, not in any order
grades = dict(John=95,Amanda=89,Jake=91,Betty=97)

# students is a list of students, sorted from lowest to highest grade
students = sorted(grades, key=lambda k: grades[k])

print 'Grades from lowest to highest:'
for student in students:
    print '{0} {1}'.format(grades[student], student)

lowest_student = students[0]
highest_student = students[-1]
print 'Lowest grade of {0} belongs to {1}'.format(grades[lowest_student], lowest_student)
print 'Highest grade of {0} belongs to {1}'.format(grades[highest_student], highest_student)

The secret sauce here is in the sorted() function: instead of sorting by keys, we sorted by values.