Sorting Nested list in python

Question

I am doing a problem that my school has assigned to me. Here is code till now:

profits = [1,2,5,6]
weights = [2,3,4,5]
n = 8
ratio = []
count = 0
for i in range(len(profits)):
    ratio.append([])
for i in range(len(ratio)):
    ratio[i].append(weights[i])
    ratio[i].append(profits[i] / weights[i])

The output (ratio):

[[2, 0.5], [3, 0.6666666666666666], [4, 1.25], [5, 1.2]]

But the problem is that I want the list to be sorted maximum ratio wise like this:

[[4, 1.25], [5, 1.2], [3, 0.6666666666666666], [2, 0.5]]

BrokenBenchmark · Accepted Answer · 2022-04-12 04:13:04Z

1

You can pass a key parameter to .sort().

Below your current code, add:

ratio.sort(key=lambda x: x[1])

to sort on the ratio (as opposed to the default sorting mechanism, which starts at the first element in the list).

After this sorting operation, ratio will be:

[[2, 0.5], [3, 0.6666666666666666], [5, 1.2], [4, 1.25]]

answered Apr 12, 2022 at 4:13

BrokenBenchmark

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Comments

tshiono · Accepted Answer · 2022-04-12 04:23:22Z

1

Please try:

print(sorted(ratio, key=lambda x: float(x[1]), reverse=True))

Output:

[[4, 1.25], [5, 1.2], [3, 0.66666666666666663], [2, 0.5]]

answered Apr 12, 2022 at 4:23

tshiono

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1 Comment

Red_Haired_Shanks Over a year ago

I already did it but thanks for your answer.

Kshitij Verma · Accepted Answer · 2022-04-12 06:13:39Z

1

you can try sorting by the ratios and then reverse the list

def key(e):
# To sort by the 2nd element
  return e[1]

profits = [1,2,5,6]
weights = [2,3,4,5]

ratio =[]
for i in range(len(profits)):
    ratio.append([])
for i in range(len(ratio)):
    ratio[i].append(weights[i])
    ratio[i].append(profits[i] / weights[i])

print(ratio)
ratio.sort(key=key)
ratio = ratio[::-1]
print(ratio)

answered Apr 12, 2022 at 6:13

Kshitij Verma

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3 Comments

Red_Haired_Shanks Over a year ago

Why sorting the first element and what does this do: ratio.sort(key=key)

Kshitij Verma Over a year ago

key parameter of sort() function takes some function(which you can define) as value. sorting will happen based on the return of this function. for example, if you want to sort a bigger 2d list on the basis of its 3rd element def key(e): return e[2] ratio.sort(key=key)

Red_Haired_Shanks Over a year ago

OK. Thanks I get it now.

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