How could we access the value in a dictionary that is present as a list?

Question

marks={'A':[50,70,90],'B':[60,80,70],'C':[70,80,90]}

In the above dictionary, I need to access the value of B and to find the average of list (i:e:(60+80+70)/3). How could I access the value and find the average? What I tried was...

marks={'A':[50,70,90],'B':[60,80,70],'C':[70,80,90]}
get_name=input()
for i in marks:
    if i==get_name:
        for j in i:
            add += marks[j]
print(add/3)

It shows up error. How to access the values in the dictionary of the list[60,80,70] with respect to key 'B'.

Use `marks.items()`. But probably `marks[get_name]` would be better. — Olvin Roght, Jul 15 '20 at 07:21
`for j in marks[i]`. Also, you need to initialize the variable `add` to 0. Moreover, `j` IS the mark, so you need `add += j`. — Mario Camilleri, Jul 15 '20 at 07:22

score 0 · Answer 1 · answered Jul 15 '20 at 07:21

0

Here's a one liner -

avg = sum(marks['B'])/3

answered Jul 15 '20 at 07:21

WeaselFox

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`len(marks['B'])`? – Olvin Roght Jul 15 '20 at 07:23
yeah probably better, although his example has always 3 numbers so hard to tell – WeaselFox Jul 15 '20 at 07:24
So if it had n examples then the code can be `sum(marks['B'])/len(marks['B']) ` – Krithick S Jul 15 '20 at 07:29

score 0 · Answer 2 · answered Jul 15 '20 at 07:23

0

sum() will total the value in that respective list and you just have to divide it by the size of the list.

input = 'A'
average = sum(marks[input])/len(marks[input])

answered Jul 15 '20 at 07:23

Cheang Wai Bin

133
1
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score 0 · Answer 3 · answered Jul 15 '20 at 07:23

marks={'A':[50,70,90],'B':[60,80,70],'C':[70,80,90]}

For the above code, marks[get_name] should print out the list [60,80,70] through which the mean can be then taken.

To iterate over a dictionary you would use, for key, val in marks.items() and check if the provided user input equals to one of the key and then take the average.

How could we access the value in a dictionary that is present as a list?

3 Answers3