Python: Calling a variable defined within a function as an input

Question

I am attempting to call a value that is defined within a dictionary creation function. The current issue is the calling of i as an input when it is not defined.

Current code:

mass_list=[10.0,15.0,20.0]
def dict_by_masslist(mass_list,input_value):
 dict_created=[]
 for i in mass_list:
 dict_created.append((i,inputvalue))
 dict_created=dict(dict_created)
 return dict_created
pt_dict_pre_names=dict_by_masslist(mass_list,'pt_'+str(int(i))+'_pre')

Goal output:

pt_dict_pre_names = {10.0: 'pt_10_exp', 15.0: 'pt_15_exp', 20.0: 'pt_20_exp'}

This function will be used to not only name things but generate dictionaries of data. When used outside of the function this scripts works as expected.

Answer 1

Just use a dictionary comprehension instead:

 mass_list = [10.0, 15.0, 20.0]
 pt_dict_pre_names = {x: 'pt_{}_exp'.format(int(x)) for x in mass_list}

What happens here: for every number in mass_list we map the number to a string pt_number_exp that is formatted to include the actual number.