Question

There’s a part of the selection sort algorithm that I don’t understand. In the latter part of the code (where the temp variable is used, why are L[i] and L[minIndx] assigned values? Aren’t those values themselves? Can’t only variables be assigned values?

def selSort(L):
    for i in range(len(L) - 1):
        minIndx = i
        minVal = L[i]
        j = i+1
        while j < len(L):
            if minVal > L[j]:
                minIndx = j
                minVal = L[j]
            j += 1
    # aren’t L[i] and L[minIndx] values? How can they be assigned to new values?
        if minIndx != i:
            temp = L[i]
            L[i] = L[minIndx]
            L[minIndx] = temp

Answer 1

L[0] for example references a value or reference … if you have an array L=[10,20,30] … L[0] references the value 10 and when you do L[0] the result will be the value of the referenced index – 10 … when you do L[0] = 100 … this value for index 0 will be changed to 100. you can not do 10 = 100 because 10 is a constant value, not a variable, but you can do L[0] = 100 because L[0] references a place in the array.