How to find the index for the second minimum number in a list?-CodePudding

I have a list with 2 minimum numbers and I am trying to get the index of the minimum number 33 at index [5], but my loop stops at [0] once it's found the min. Unsure how to get the get last index value.

    rain_data =  [33, 57, 60, 55, 53, 33]
    min_value = rain_data[0]
    min_index = 0

    def minimum(rain_data)
    for val in range(len(rain_data)):
        if rain_data[val] < min_value:
            min_value = rain_data[val]
            min_index = val
    # display the min value and index
    print(min_value)
    print(min_index)
    results = (float(min_value) , min_index)

I have ran the loop and it stops at [0] and not the desired [5] index

CodePudding user response：

Try using <= min_value, then your answer will be 5. Or make your min_index of type array, so you can store all the indexes in the array, so you will get a list of all the indexes where the minimum is found.

CodePudding user response：

rain_data = [33, 57, 60, 55, 53, 33]
minimum = min(rain_data)
out = [i for i,x in enumerate(rain_data) if x == minimum]
print(out[-1])

rain_data = [33, 57, 60, 55, 53, 33]
min_index = (len(rain_data) - 1) - rain_data[::-1].index(min(rain_data))
print(min_index)

CodePudding user response：

As noted in comment the question can be interpreted in different ways.

position of the LAST minimum

rain_data = [33, 57, 60, 55, 53, 33]

min_value = rain_data[0]
last_min_pos = 0
for i, x in enumerate(rain_data):
    if x <= min_value:
        min_value = x
        last_min_pos = i

Output: 5

position of the NTH minimum (here second)

I would use a dictionary/list to keep track of the positions of each item and a loop to compute the min value.

This logic requires to read the list only once.

With a dictionary:

rain_data = [33, 57, 60, 55, 53, 33]

d = {}
min_val = rain_data[0]
for i, x in enumerate(rain_data):
    if x < min_val:
        min_val = x
    d.setdefault(x, []).append(i)

if len(d[min_val])>1:
    print(d[min_val][1])

Output: 5

Same logic with a list:

l = []
min_val = rain_data[0]
for i, x in enumerate(rain_data):
    if x < min_val:
        min_val = x
        l = []
    if x == min_val:
        l.append(i)

if len(l)>1:
    print(l[1])