Inserting item in string after specific word

Question

I want to write a function that takes a string, finds the tsp or tbsp format, and converts that to gram.

Then, I store this information in c and have to insert it behind the tbsp/tsp word in the string. Since strings are immutable I was thinking of converting it to a list first, but now I am a bit stuck.

Anyone has advice on how to do this? :)

Examples:

 input                   output

"2 tbsp of butter" --> "2 tbsp (30g) of butter"

"1/2 tbsp of oregano" --> "1/2 tbsp (8g) of oregano"

"1/2 tsp of salt" --> "1/2 tbsp (3g) of salt"

def convert_recipe(recipe):

    c = ''

    for i in recipe: # save the digit
        if i.isdigit():
            c += i
    if 'tsp' in recipe: # convert tsp to gram
        c = int(c) * 5
    elif 'tbsp' in recipe: # convert tbsp to gram
        c = int(c) * 15

    # now we have c. Insert (c) behind tsp / tbsp in string    


recipe = recipe.split()
print(recipe)
convert_recipe("2 tbsp of butter")

if "1/2 tbsp" is once (8g), once (3g) and "2 tbsp" are (30g), something is seriously wrong with tbsp-math. — Ma0
– Ma0, Commented Apr 27, 2018 at 10:15
@Ev.Kounis "Given all the measures in tablespoon (tbsp) and in teaspoon (tsp), considering 1 tbsp = 15g and 1 tsp = 5g, append to the end of the measurement the biggest equivalent integer (rounding up)" — Steve
– Steve, Commented Apr 27, 2018 at 10:23
Could have added that to the question; it would have saved much time. — Ma0
– Ma0, Commented Apr 27, 2018 at 10:27

Ma0 · Accepted Answer · 2018-04-27 11:03:51Z

1

Here is a solution that should cover most cases.

from fractions import Fraction
from math import ceil

def convert_recipe(recipe): 
    weight = {'tbsp': 15, 'tsp': 5}  # store the weights for tsp and tbsp
    ts = 'tbsp' if 'tbsp' in recipe else 'tsp'
    temp = recipe.split()            # convert string to list
    quantity = float(Fraction(temp[temp.index(ts)-1]))
    new_recipe = recipe.replace(ts, '{} ({}g)'.format(ts, ceil(quantity*weight[ts])))  # see (1)
    return new_recipe


print(convert_recipe("2 tbsp of butter"))   # -> 2 tbsp (30g) of butter
print(convert_recipe("1/2 tbsp of butter")) # -> 1/2 tbsp (8g) of butter
print(convert_recipe("1/2 tsp of salt"))    # -> 1/2 tsp (3g) of salt

(1): here are are actually replacing the 'tbsp' part of the sentence with 'tbsp (30g)' for example. The string that is inserted ('tbsp (30g)') is a result of string formating.

edited Apr 27, 2018 at 11:03

answered Apr 27, 2018 at 10:25

Ma0

15.2k4 gold badges38 silver badges70 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

Steve Over a year ago

Nice, thank you. Could you ellaborate on this part --> recipe.replace(ts, '{} ({}g)'.format(ts, ceil(quantity*weigt[ts]))) or a resource where I could read about it?

Steve Over a year ago

Oh and this part as well : float(Fraction(temp[temp.index(ts)-1]))

Steve Over a year ago

I don't know why but this sentence does not return the right answer. "Add to the mixing bowl and coat well with 1 tbsp of olive oil & 1/2 tbsp of dried dill"), -- should be "Add to the mixing bowl and coat well with 1 tbsp (15g) of olive oil & 1/2 tbsp (8g) of dried dill"

Ma0 Over a year ago

@Daphne because multiple instances are not supported. The quantity is defined by the first occurrence. The examples provided in the question and the question body did not hint towards such a use case.

Nannan AV · Accepted Answer · 2018-04-27 10:36:48Z

0

if 'tsp' in recipe:                  (1)
    c = int(c) * 5
    recipe = recipe.split('tsp')     (2)
    recipe = recipe[0] + 'tsp (' + str(c) + 'g)' + recipe[1]

// similar code for tbsp

I believe this will work for you?

Edit:

at (1), recipe = "1/2 tsp of salt"

at (2), recipe becomes ["1/2 ", " of salt"]

And then its all about adding the strings back together

The split method splits the string based on the given argument and returns an array of strings

edited Apr 27, 2018 at 10:36

answered Apr 27, 2018 at 10:21

Nannan AV

4197 silver badges23 bronze badges

5 Comments

Steve Over a year ago

It works! thank you. Could you describe what happens when you do recipe.split('tsp') ?

Ma0 Over a year ago

how does this deal with Fractions?

Nannan AV Over a year ago

I haven't changed the logic behind calculating c.

Ma0 Over a year ago

@NannanAV There was no logic behind the calculation of c (c = '')

Nannan AV Over a year ago

I didn't get what you meant by "How does this deal with Fractions?"

Collectives™ on Stack Overflow

Inserting item in string after specific word

2 Answers 2

4 Comments

5 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

4 Comments

5 Comments

Your Answer

Sign up or log in

Post as a guest

Related