How to say something when the specific value you are looking for is not in the list
I am working on this assignment for school and have gotten almost everything, but I am missing a very small but important part.
So the full purpose is for the user to enter some values for the grades that the student is listed, then the user should be able to see the average of a particular subject, or a printed version of all grades that all students received the subject.
My problem is how can I tell the user something that there are not any values for a particular item when she selects to view the avg / all values for that item. I will show here what I have with a list that already has some values, so there is no need to go through the whole process to put them in
cijfers = [ [ 12345, 'wiskunde', 8.9], [ 12345,'elnet', 4.0], [12345, 'python', 8.9], [98761, 'wiskunde', 6.5], [98761, 'elnet', 7], [98761, 'python', 4.5], [20945, 'wiskunde', 5],[20945, 'elnet', 6.9], [20945, 'python', 4.5], [65489, 'wiskunde', 3.4], [65489, 'elnet', 6.7], [65489, 'python', 10]]
The first is the student's number, the second is the subject, and the third is the grade that that particular student received.
so if i put this to give me all the scores for "wiskunde"
cijfers = [ [ 12345, 'wiskunde', 8.9], [ 12345,'elnet', 4.0], [12345, 'python', 8.9], [98761, 'wiskunde', 6.5], [98761, 'elnet', 7], [98761, 'python', 4.5], [20945, 'wiskunde', 5],[20945, 'elnet', 6.9], [20945, 'python', 4.5], [65489, 'wiskunde', 3.4], [65489, 'elnet', 6.7], [65489, 'python', 10]]
a = 0
print (' Tentamencijfers voor: ','Wiskunde', '\n', '========================================')
print (' studenten# | cijfer')
while (a<len(cijfers)):
if (cijfers [a][1] == 'wiskunde'):
print (' ',cijfers[a][0], ' ',cijfers[a][2])
a = a + 1
It gives me the following output:
Tentamencijfers voor: Wiskunde #translates to exam grades for: Math
========================================
studenten# | cijfer
12345 8.9
98761 6.5
20945 5
65489 3.4
What it should do, but let's say that there were no values for "wiskunde", so the list would look like this:
cijfers = [ [ 12345,'elnet', 4.0], [12345, 'python', 8.9], [98761, 'elnet', 7], [98761, 'python', 4.5], [20945, 'elnet', 6.9], [20945, 'python', 4.5], [65489, 'elnet', 6.7], [65489, 'python', 10]]
This will give me this as a result:
Tentamencijfers voor: Wiskunde #translates to exam grades for: Math
========================================
studenten# | cijfer
I know it shows it a bit because I wrote the "print" function before the "while", but that's not my question.
So my question is, how can I get him to give me just "There are no values for this particular item"?
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To strictly answer your question, I would add a counter and change the loop like this:
count = 0
for i in cijfers:
if (cijfers i[1] == 'wiskunde'):
count += 1 # Same as count = count + 1
print (' ',i[0], ' ',i[2])
#Out of the loop:
if count == 0:
print "There no values put in for this particular subject"
As a data structure, I think the dictionary will better suit your needs, using the student number as the key; check them out!
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Well I'm not at all sure if this is what you want, but it works
print (' Tentamencijfers voor: ','Wiskunde', '\n', '========================================')
lines_studient = []
found = False
for entry in cijfers:
if (entry[1] == 'wiskunde'):
lines_studient.append(' '+str(entry[0])+ ' '+str(entry[2]))
found = True
if not found:
print (' None studients')
else:
print (' studenten# | cijfer')
for line in lines_studient:
print(line)
It uses two loops, the first to find if one item exists, and the second to print strings.
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Try it. You don't need to use two for the loops here. You can use comprehension with any () method:
cijfers = [ [ 12345, 'wiskunde', 8.9], [ 12345,'elnet', 4.0], [12345, 'python', 8.9], [98761, 'wiskunde', 6.5], [98761, 'elnet', 7], [98761, 'python', 4.5], [20945, 'wiskunde', 5],[20945, 'elnet', 6.9], [20945, 'python', 4.5], [65489, 'wiskunde', 3.4], [65489, 'elnet', 6.7], [65489, 'python', 10]]
a = 0
print ' Tentamencijfers voor: ','Wiskunde', '\n', '========================================'
print ' studenten# | cijfer'
if any("wiskunde" in sublist for sublist in cijfers):
while (a<len(cijfers)):
if (cijfers [a][1] == 'wiskunde'):
print ' ',cijfers[a][0], ' ',cijfers[a][2]
a = a + 1
else:
print "There no values put in for this particular subject"
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