This time we're working with dictionaries. In fact, we're working with a speci c dictionary in all three functions: This dictionary maps a username to a list of last name, rst name, e-mail, age and gender. We will build the dictionary from a le, update the dictionary, and then select elements from the dictionary that meet a certain criteria.
Building the Dictionary
Write a function named create dict, that takes one parameter, an open le handle (remember ex5, this is an open le handle, not the name of a le), and returns a dictionary that maps a string to a list of strings and ints. In particular, the type contract of this function will be:
(io.TextIOWrapper) - dict of fstr: [str, str, str, int, str]g
This function will read a le formatted like the provided ex7 data.txt. That is, each line will have a username, rst name, last name, age, gender (either M, F or X) and an e-mail address, all separated by spaces. The function will insert each person's information into a dictionary with their username as the key, and the value being a list of [last name, first name, e-mail, age, gender]. When the entire le has been processed, it will then return the dictionary.
Changing the Dictionary
Write a function called update field, that takes 4 parameters: A dictionary in the format created by the previous function, a username, the name of a eld1 (One of: 'LAST', 'FIRST', 'E-MAIL', 'AGE' or 'GENDER'2), and a new value to replace the current value of the speci ed eld. The function should not return anything, but instead mutate the dictionary as appropriate.
An example call of the function is below:
my_dict = { sclause :[ Clause , Santa , santa@christmas.np , 450, M ]}
update_field(my_dict, sclause , AGE , 999)
my_dict == { sclause : [ Clause , Santa , santa@christmas.np , 999, M ]}
True
BONUS: Selecting Elements
Write a function called select that takes 4 parameters, a dictionary formatted as in the previous questions, the name of a eld to select, the name of a eld to check 3, and a value to check for.
The function should return a set of all the data elements from the selected elds of people whose checked elds were equal to the checked value. That was a bit of a mouthful, so let's see an example to make it clearer. We want to select the e-mail of anyone whose gender is equal to M:
my_dict = { sclause :[ Clause , Santa , santa@christmas.np , 450, M ], ebunny :[ Bunny , Easter , bunny@easter.hop , 99, M ], tfairy :[ Fairy , Tooth , fairy@money4teeth.net , 0, F ]}
select(my_dict, E-MAIL , GENDER , M )
{ santa@christmas.np , bunny@easter.hop }
You may want to write a helper function to get the index given the eld name, particularly if you're going to try the bonus question
2Make sure you tell the user that these are the options you're expecting. As long as you inform them, your code doesn't have to work with other inputs, though it still shouldn't crash.
3 eld names and rules are the same as in the previous function
1
