String manipulation based on lists

February 6, 2022

Hello I need to write a function that will automatically make a specific string

For example I have a List of elements:

tab = [12, 23, 13, 4, 2]

I want the function to take each element and add it to a string like so:

string:

12 + 23x + 13x^2 + 4x^3 + 2x^4

Basically, rewrite 1st element then add 'x' to the 2nd and every other but every element after 2nd must be raised to the power (starting with 2 on the third element and increasing by 1 for each next element)

The list can be infinitely long and it can contain floats so the function has to be universal

I tried this:

tab = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

string = ""
num = 0
for x in tab:

    if num < 1:
        string = string + str(x) + ' ' + '+' + ' '
    elif num < 2:
        string = string + str(x) + 'x' + ' ' + '+' + ' '
    else:
        string = string + str(x) + 'x' + f'^{num}' + '+' + ' '
    num = num + 1

print(string)

output:

'1 + 2x + 3x^2+ 4x^3+ 5x^4+ 6x^5+ 7x^6+ 8x^7+ 9x^8+ 10x^9+'

>Solution :

I think this is the simplest code to do this. Initiate the output_string with the first number that is cast to be a string. Then, iterate on other elements of the list and do concatenation of +x^index to the output_string:

tab = [12, 23, 13, 4, 2]
output_string = str(tab[0])
for each_index in range(1, len(tab)):
    output_string += " + " + str(tab[each_index]) + "x^" + str(each_index)
print(output_string)

The output: