如何找到列表中最大和最小数字的位置？

Question

For this assignment I need to write a program that will ask the amount of rainfall for each month. The user enters the amount and that gets appended to a list. After the data is gathered for each month, the program will calculate and output the total rainfall, average rainfall, the month with the highest rainfall and the month with the lowest rainfall. The part I'm having trouble with is returning the months with the highest and lowest rainfall. I don't want to use the sort method because I plan on using the maxRain function to go through the rainList to find the highest value and return the position. Then in the main function print the month of the corresponding position from the months list. Unless there is another way to assign that amount of rainfall to that month and return it another way.

# PURPOSE:  This program lets the user enter the total rainfall for each of
#           of 12 months then calculates total, average, min and max rainfall

months = ["January", "February", "March", "April", 
          "May", "June", "July", "August", 
          "September", "October", "November", "December"]

# function that gets amount of rainfall for each month and appends it to a list
def getRainFall():
    nums = []
    for i in range(len(months)):
        m = months[0+i]
        print("Enter the rainfall for ", m)
        x = input()
        x = float(x)
        nums.append(x)
        
    return nums

# function that adds the numbers of the list and returns the sum
def totalRain(nums):
    total = 0
    for num in nums:
        total = total + num
    return total

# function to calculate and return the average of numbers from a list
def mean(nums):
    total = 0.0
    for num in nums:
        total = total + num
    return total / len(nums)

def maxRain(nums):
    for i in range(len(nums)):
        if nums[i] > nums[i+1]:
            x = nums[i]
        else:
            x = nums[i+1]
    return x
    
#def minRain(nums):
    
def main():
    rainList = getRainFall()
    rainAverage = mean(rainList)
    total = totalRain(rainList)
    highest = maxRain(rainList)
    #lowest = minRain(rainList)
    print("Total rainfall:", total) 
    print("Average rainfall:", rainAverage)
    print("Highest rainfall:", highest)
    #print("Lowest rainfall:", lowest)

    # close the program
    input("Press the <Enter> key to quit")

main()

Answer 1

To answer the core question:

nums =  [32, 37, 28, 30, 37, 25, 27, 24, 35, 55, 23, 31, 55, 21, 40, 18, 50, 35, 41, 49,
         37, 19, 40, 41, 31]

list_min, list_max = min(nums), max(nums)

mins = [i for i, j in enumerate(nums) if j == list_min]
maxs = [i for i, j in enumerate(nums) if j == list_max]

print(f'{mins=}, {maxs=}')  $ -> mins=[15], maxs=[9, 12]

Answer 2

So I've altered your code a fair bit, which I don't usually like to do because I think it's less helpful. In this case however it just makes the whole process much simpler.

This uses builtin python functions to do what you are manually doing.

months = ["January", "February", "March", "April", 
          "May", "June", "July", "August", 
          "September", "October", "November", "December"]

# function that gets amount of rainfall for each month and appends it to a list
def getRainFall():
    nums = []
    for month in months:
        m = month
        print("Enter the rainfall for ", m)
        x = input()
        x = float(x)
        nums.append(x)
        
    return nums
    
def main():
    rainList = getRainFall()
    total = sum(rainList)
    rainAverage = total/len(rainList) # Sum/number of points
    highest = months[rainList.index(max(rainList))] # Max rain index into months arr
    lowest = months[rainList.index(min(rainList))] # Min rain index into months arr
    
    print("Total rainfall:", total) 
    print("Average rainfall:", rainAverage)
    print("Highest rainfall:", highest)
    print("Lowest rainfall:", lowest)

    # close the program
    input("Press the <Enter> key to quit")

main()

Sample output:

Enter the rainfall for  January
1
Enter the rainfall for  February
2
Enter the rainfall for  March
3
Enter the rainfall for  April
45
Enter the rainfall for  May
5
Enter the rainfall for  June
6
Enter the rainfall for  July
7
Enter the rainfall for  August
8
Enter the rainfall for  September
9
Enter the rainfall for  October
0
Enter the rainfall for  November
1
Enter the rainfall for  December
2
Total rainfall: 89.0
Average rainfall: 7.416666666666667
Highest rainfall: April
Lowest rainfall: October
Press the <Enter> key to quit

Answer 3

You maxRain does not work because of this nums[i+1] , when i is in the last index you ask for the next and that give you an error, to fix it start you range in 1 (range(1,len(nums)) and change yours [i] for [i-1] and your [i+1] for [i] or end it up on len(nums)-1 to avoid this problem.

Regarless the above solution you take, in this function you can also keep track of the index and return it with the value, because can return more than one value if you put in inside a tuple or some other object, is a simple as return index,x or return (index,x) if you prefer it with the parenthesis

Alternatively, you can easily use the build-in enumerate alongside a key function to get both the index and the maximum or minimum elements of a given list with max or min

>>> nums=[1,2,34,4,25,0,3]
>>> max(enumerate(nums),key=lambda x:x[1])
(2, 34)#index, element
>>> min(enumerate(nums),key=lambda x:x[1])
(5, 0)
>>> 

a key function is no more than a function that take and elements of your list or iterable (anything that you can call iter on) and extract or transform it into the thing we want it to be compared by, which in the example is...

>>> list(enumerate(nums))
[(0, 1), (1, 2), (2, 34), (3, 4), (4, 25), (5, 0), (6, 3)]
>>> 

...the second element of the tuple we get from enumerate, the lambda part is a way to declare simple anonymous functions so we don't have to do the following and use that instead

def second_elem(obj):
    return obj[1]

---

Another thing is that you can use a list directly in a for loop, no need to do it over a range on the len of the list

>>> months = ["January", "February", "March", "April", 
      "May", "June", "July", "August", 
      "September", "October", "November", "December"]
>>> for month in months:
        print(month)

    
January
February
March
April
May
June
July
August
September
October
November
December
>>> 

the same is true for many more object, such as tuple, dict, str, etc, any iterable really

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Your mean and totalRain function aren't wrong but can be make simpler by using the sum function