This program was written in 2021 as part of an introductory programming course at Penn State – University Park
The purpose of this program is to create a dynamic recipe scaler that accepts an unlimited number of inputs from the user. The output is a dynamically formatted recipe utilizing mixed fractions that have been scaled according to user needs.
Learning Outcomes:
- Utilize lists, list functions, and list indexes
- Address a multi-branched logic problem and determine most concise operational routes for solutions to all branches
- Format output with mixed fractions, text, and multiple columns
print("This is a recipe scaler for serving large crowds!")
print("")
#setting up lists to hold keyboard inputs
quant_list = []
unit_list = []
item_list = []
#KEYBOARD INPUTS
raw_line = input("""Enter one ingredient per line, with a numeric value first.
Indicate the end of the input with an empty line:
""")
while raw_line != "":
#will end input after detecting empty line
if raw_line.count(" ") == 1:
#handles unitless ingredients (such as eggs)
quant, item = raw_line.split(' ')
quant_list.append(quant)
unit_list.append(" ")
item_list.append(item)
else:
quant, unit, item = raw_line.split(' ',2)
#split the line input into 3 values
#next add values to appropriate lists
quant_list.append(quant)
unit_list.append(unit)
item_list.append(item)
raw_line = input("")
#repeat input for next ingredient
#prints recipe with formatting
print("Here is the recipe that has been recorded:")
k=0
while k < len(quant_list):
print(format(quant_list[k], "^7") + format(unit_list[k], "8") + format(item_list[k]))
k = k + 1
#KEYBOARD INPUTS
servings = int(input("How many does this recipe serve? "))
people = int(input("How many people must be served? "))
#calculate how much to multiple recipe by
multiplier = people//servings
if people % servings != 0:
multiplier = multiplier +1
#forces the program to always round up
print(f"""Multiplying the recipe by {multiplier}
""")
Because recipes frequently utilize fractions (like 1/2 tsp vanilla extract or 3/4 cup flour), scaling the recipe is more difficult than simply multiplying the inputted quantity numbers by the calculated multiplier.
There are a few ways the program can play out:
- INTEGERS: the easiest case, requires simply multiplying quantity by multiplier.
- FRACTIONS: requires multiplying only the numerator, then may or may not require simplifying
- FRACTIONS <1: these cannot be mixed and can be added directly to the output
- FRACTIONS =<1: these need to be simplified
- MIXED: will result in a combination of integers and fractions
- WHOLE: simplify to whole number integer
scaled_list = []
for i in quant_list:
#separate integers from fractions based on presence of "/"
if "/" in i:
numer, denom = i.split('/')
numer = int(numer)
denom = int(denom)
numer = numer * multiplier
#separate out fractions that need to be simplified
if numer // denom >= 1:
whole = numer // denom
whole = str(whole)
#identifies and simplifies mixed fractions
if numer % denom != 0:
part_numer = numer % denom
part_numer = str(part_numer)
denom = str(denom)
remainder = part_numer + "/" + denom
mixed_fraction = whole + " " + remainder
#takes remaining fractions and simplifies to whole numbers
else:
mixed_fraction = whole
scaled_list.append(mixed_fraction)
#takes fractions <1 and assembles them for output
else:
numer = str(numer)
denom = str(denom)
fraction = numer + "/" + denom
scaled_list.append(fraction)
#remaining numbers are integers
#can be multiplied and passed to output
else:
i = int(i)
i = i * multiplier
scaled_list.append(i)
#OUTPUT
#print new recipe
n=0
while n < len(quant_list):
print(format(scaled_list[n], "^7") + format(unit_list[n], "8") + format(item_list[n]))
n = n + 1
#print number of servings for scaled recipe
print(f"""
Serves {servings * multiplier}""")
This is how the final program looks:
