I want to select the minimum value of a nested list of the second element (the float part).
Code
n=int(input("Enter the number: "))
arr=[[input(),float(input())] for _ in range(0,n)]
arr.sort(key=lambda x: (x[1],x[0]))
min_val=min(arr)
print(min_val)
Input
Enter the number: 3
arp
5
grp
4
drp
3
Output
['arp', 5.0]
Expected output
['drp',3.0]
You calculate the minimum with:
n = int(input("Enter the number: "))
arr = [[input(),float(input())] for _ in range(0,n)]
arr.sort(key=lambda x: (x[1],x[0]))
min_val=min(arr)
print(min_val)This means that you will perform a loop over the list, and obtain the smallest element. Since you did not provide a key, Python will sort, like it sorts tuples by default: first by first element, and in case of a tie by second element and so on.
In case you want the minimum according to a specific key, you need to use the key parameter of the min function:
n = int(input("Enter the number: "))
arr = [[input(),float(input())] for _ in range(0,n)]
min_val=min(arr, key=lambda x: (x[1],x[0]))
print(min_val)Note that obtaining the minimum is usually faster than sorting the list. If you do not need to sort the list, you can drop it, and simply use min(..) (like here).
In case you need to sort the list anyway, the smallest element is the first element of the list, so you can obtain it with:
n = int(input("Enter the number: "))
arr = [[input(),float(input())] for _ in range(0,n)]
arr.sort(key=lambda x: (x[1],x[0]))
min_val=arr[0]
print(min_val)
Use min with key as Willem Van Onsem suggested and apply filter to your sequence:
arr=[("a",2),("b","5"),("c",1),("a",2),("b","5"),("c",1)]
# get minimal value
min_val=min(arr, key= lambda x:(x[1],x[0]))
# filter all with 2nd element euqal to minimals 2nd elemenbt
withoutMin = filter(lambda x: x[1] != min_val[1], arr)
# or use equivalent list comp:
# without = [x for x in arr if x[1] != min_val[x]]
print(arr)
print(withoutMin)
Output:
[('a', 2), ('b', '5'), ('c', 1), ('a', 2), ('b', '5'), ('c', 1)]
[('a', 2), ('b', '5'), ('a', 2), ('b', '5')] # filtered
since the array is already sorted:
print(arr[0])
OR
min_val=min(arr)
will sort by the first element. To sort by second element, change it to:
min_val=min(arr, key = lambda t: t[1])
min(..)does not care about the key, it sorts the tuples like tuples are sorted by default.arr[0]