Arithmetic-formatter help please

Python
1

I cannot understand the block below which I put in [[[[[ ]]]]]]]. What does :> do? Thanks :slight_smile:

def arithmetic_arranger(problems, *args):  # * allows multiple input of items in sequence, Python interpolator.
    if len(problems) > 5:
        return "Error: Too many problems."

    arranged_problems = [ ]

    for index, value in enumerate(problems):
          #[“32”, “+”, “8”]  value is the set to split.
        operation = value.split(" ")

        if operation[1]  not in  "-+":  # 0 = position 1, 1 = position 2...in Python, so 1st number +/- 2nd number
            return  "Error: Operator must be '+' or  '-'."

        if len(operation[0]) > 4 or len(operation[2])  >  4:  # both numbers must be less than 4.
            return  "Error: Numbers cannot be more than four digits."

        try:   #try-except block to check if all are integers.
            value_1 = int(operation[0])
            value_2 = int(operation[2])
        except  ValueError:   # A Python keyword to check if all int.
            return  "Error: Numbers must contain only digits."

#calculate the length of each line
        longest_val = max(len(operation[0]), len(operation[2]))
        width = longest_val + 2  # the 2 adds spacing to len < 5 above.

#operation = [“32”, “+”, “8”]
#output =  f"{operation[0]:>{width}}\n{f’{operation[1]} {operation[2]}’:>{width}}\n{‘-’*width}”

[[[[[[[L1 = (f"{operation[0]  :>  {width}}”
      # " is Python interpolation or selective insertion.
L2 = operation[1] + f"){operation[2] :> {width-1}}”
d =  '-' * width   ]]]]]]]]]     #this block.  I can't get it.  


try:
    arranged_problems[1]  +=  (''  *  4)  +  L1
except  IndexError:
    arranged_problems.append(L1)

try:
    arranged_problems[2]  +=  (‘  ‘  *  4)  +  L2
except  IndexError:
    arranged_problems.append(L2)


try:
    arranged_problems[2]  +=  (‘  ‘  *  4)  +  d
except  IndexError:
    arranged_problems.append(d)


if args:
    “””
    #This runs if the second parameter True is passed in denoting we need to calculate the answer    value.
    “””
    ans = int(operation[0])  +  int(operation[2])  if operation[1]  ==  ‘+’  else int  (operation[0]) - int(operation[2])

a  =  f”{str(ans):>{width}}

    try:
        arranged_problems[3]  +=  (‘  ‘  *  4)  +  a
    except  IndexError:
        arranged_problems.append(a)


output = f”{arranged_problems[0]}\n
{arranged_problems[1]}\n{arranged_problems[2]}”
output = output + f”\n{arranged_problems[3]}”
if args else output

return output


# print(arithmetic_arranger([“3 + 855”, “3801 - 2”, “45 + 43”, “123 + 49”]))

# print(“      3      3801      45      123\n+ 855
    2     +  43     +     49\n-----      ------      ------     -----”)
# print(arithmetic_arranger([“32 - 698”, “1 -  3801”,  “45  +  43”,  “123  +  49”],  True))

# print(“    32        1        45        123\n-   698
  3801     +     43      +      49\n-----       ------       ----       ------\n  -666        -3800      88     172”)
2

Start a new project and try this code:

test = "test text"
width = 10
print(f"{test:>{width}}")

Experiment with different values for test and width, and see what the result is.

Try replacing the > with a < and see how it changes.

You can read more here: https://dev.to/erictleung/print-fixed-fields-using-f-strings-in-python-26ng

3

Thanks. That helps :slight_smile:

1 Like