CODEWITHSUNDEEP
pythonmatlabindexing
Mano
Mano

Reputation: 73

Filter nested list based on value of sub-list

so this question is quite complicated to explain. Say I have a list of list of list of grades and a name, for example:

    a=[[90,50,40],'Josh']
    b=[[85,60,90],'Becky']
    c=[a,b]

so that c would be:

    c=[[[90,50,40],'Josh'],[[85,60,90],'Becky']]

now let's say the list is much longer and I'm interested in a student who got a list of grades of [100,100,100]. How can I loop over that?

From my usage of MATLAB I know I used c[:][0] to get a "list" of the grades.

Now I'd like to do something as:

   target=[100,100,100]
   if target in c[:][0]:
   print 'we got a smart fella in the hood'

how can I do that in python? Thanks a lot!

Upvotes: 0

Views: 733

Answers (4)

OneCricketeer
OneCricketeer

Reputation: 191738

I would recommend going a class-based approach to get away from nested lists

class Student():
    def __init__(self, name, scores):
        self.name = name
        self.scores = scores

    def has_perfect_scores():
        return all(score == 100 for score in self.scores)

Then, 

c = [ Student('Josh', [90,50,40]), Student('Becky', [85,60,90]) ]
for student in c:
    if student.has_perfect_scores():
        print 'we got a smart fella in the hood named {}'.format(student.name)

For any student you can loop over their scores list

Upvotes: 0

Val
Val

Reputation: 65

If you need only to know if there is a match, you can do:

c=[[[90,50,40],'Josh'],[[85,60,90],'Becky']]
target = [85,60,90]
if target in [i[0] for i in c]:
    print "true"

Upvotes: 0

Prune
Prune

Reputation: 77857

According to your code, the matrix c would appear as a nested list structure. Digging down the levels ...

c[1] is [[85,60,90],'Becky']
c[1][0] is [85,60,90]
c[1][0][2] is 60

That should explain the naming to you. Now, you need to check the scores lists, c[*][0] for the target values. If you need an exact match, it's easy enough: build a temporary list of the values and report if there's a hit.

if target in [record[0] for record in c]:
    print "Smart person exists"

If you need to print a list of the names, try

print [record[1] for record in c if record[0] == target]

Does that get you moving?

Upvotes: 0

Moinuddin Quadri
Moinuddin Quadri

Reputation: 48077

You should be iterating like:

c = [[[90,50,40],'Josh'],[[85,60,90],'Becky'], [[100,100,100],'Mano']]
target = [100,100,100]

for grade, name in c:
    if grade == target:
        print name

which will print:

Mano

If you want the list of all the name satisfying the mentioned criterion, you may use a list comprehension expression as:

names = [name for grade, name in c if grade == target]

Upvotes: 4

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