Finding a next lowest number from a List in python

Question

I have a list of arrays as follows: Array =[3, 6, 5, 7, 2, 4, 3, 5, 4, 5, 4, 7, 6, 7, 1, 7, 4, 6, 3]

example: Value = 3, 6, 5, 7, 2, 4, 3, 5, 4, 5, 4, 7, 6, 7, 1, 7, 4, 6, 3

valley/Peak = v, p, v, p, v, p, v, p, v, p, v, p, v, p, v, p, v, p,v

Answer 1

logic

assign the index to start from

assign the value of the starting index

make a loop starting from the starting index to the end of the loop

in the loop check if current number is smaller than the starting target

slice the list to create the result sublist

code

array = [3, 6, 5, 7, 2, 4, 3, 5, 4, 5, 4, 7, 6, 7, 1, 7, 4, 6, 3]

start_index = 0  # the index to start from

# start_index = int(input("Enter the index to start from: ")) # to take this a step further, you could ask the user for the index to start from

target = array[start_index]  # the number in the starting index

for i in range(start_index, len(array)):  # loop from the start index till the end
    if array[i] < target:  # if the current number is smaller than my traget
        # split the list from the start index to the current index (+1 because the slice is not inclusive)
        print(array[start_index:i+1])
        break
    if i == len(array)-1:  # if we reached the end of the list
        print('fail')  # print the rest of the list

input

start_index = 0

array = [3, 6, 5, 7, 2, 4, 3, 5, 4, 5, 4, 7, 6, 7, 1, 7, 4, 6, 3]

output

[3, 6, 5, 7, 2]

Answer 2

As Mark Ransom & SA.93 suggested, indexing in python starts from 0. Maybe you are more familiar with R... :) For your solution, try this;

def next_lowest_num(Array,num):
    lst = []
    for i in Array[Array.index(num):]:
        if i >= num:
            lst.append(i)
        else:
            lst.append(i)
            break
    return lst

print(next_lowest_num(Array=[3, 6, 5, 7, 2, 4, 3, 5, 4, 5, 4, 7, 6, 7, 1, 7, 4, 6, 3],num=3))
print(next_lowest_num(Array=[3, 6, 5, 7, 2, 4, 3, 5, 4, 5, 4, 7, 6, 7, 1, 7, 4, 6, 3],num=5))

# Output
[3, 6, 5, 7, 2]
[5, 7, 2]

Hope this Helps...