how to check if value exist in dictionary

Question

The following is my dictionary. How can I check if a given value is in the dictionary. For example, if user enter a number 129, then, how do I check if the number exist in either key A or B?

studentData = {
          'A': [127, 104],
          'B': [128,  204, 205, 118]
       }

if studID <= 0 :
    print ('Invalid id. Student id must be positive')
    studID = int(input('Enter student id: '))
elif studID in studentData.values() == True:   # how to check if input exist?
    print (f'fail')        
else:
    studentData[modCode].append(int(studID))
    print ("complete")     
    break

`if number in studentData['A'] or number in studentData['B']`? — mkrieger1, Aug 25 '20 at 15:12
`studentData.values()` gives a list of (lists of ints). You need to check if `studID` is in _each_ of the (list of int). You currently just check if `studID` is in the list of lists (which it obviously isn't, because `studID` is an `int` which isn't in the list of lists) — Pranav Hosangadi, Aug 25 '20 at 15:15
@GreenCloakGuy, "You need to do this and here's why" helps more than "Do this". — Pranav Hosangadi, Aug 25 '20 at 15:17
https://stackoverflow.com/questions/8214932/how-to-check-if-a-value-exists-in-a-dictionary-python — George, Aug 25 '20 at 22:00
Does this answer your question? [How to check if a value exists in a dictionary (python)](https://stackoverflow.com/questions/8214932/how-to-check-if-a-value-exists-in-a-dictionary-python) — George, Aug 25 '20 at 22:01

score -2 · Answer 1 · answered Aug 25 '20 at 15:14

Assuming the following:

studentData = {
    'A': [127, 130, 123, 210, 109, 128, 204, 206, 111, 129, 103, 116, 112, 209, 122, 202, 121, 101, 113, 104],
    'B': [128, 206, 101, 111, 127, 119, 113, 207, 117, 204, 106, 123, 103, 105, 205, 118]
}

And that modCode contains either 'A' or 'B':

if studID <= 0 :
    print ('Invalid id. Student id must be positive')
    studID = int(input('Enter student id: '))
elif studID in studentData[modCode]:   # how to check if input exist?
    print (f'Add to Enrolment operation failed. Student is already enrolled in {modCode}')        
else:
    studentData[modCode].append(studID)
    print ("Add to Enrolment operation has successfully completed")

score -2 · Answer 2 · answered Aug 25 '20 at 15:15

-2

you can easily check with the "in" statement within the value of the key

for key in ['A', 'B']:
    print(studID in studentData[key])

answered Aug 25 '20 at 15:15

Eren Yaegar

41
3

how to check if value exist in dictionary

2 Answers2