[Tutor] Playing with generators

[Leam Hall]

Hello Avi!

I apologize for the use of "peeps"; I try to avoid slang terms when talking to an international group. My brain didn't wake up this morning, and I missed fixing that.

The task is to learn generators, and I tried to minimize the code to focus on my main question, "can a generator return a key and an object as a value, such that the key is an attribute of the value object?" My code, while it needs work, proves that it the generator can.

I'm not sure that your code line meets that question:  return { datum.get('fname', 'missing'): Person(datum) for datum in data }   Specifically, it seems to be using 'fname' from datum, not from the object. As you said, the first name is not a good key, the object will eventually create a better one from the data provided. I used fname in the example to keep the code sample short, but to show that I had actually done some work on the question.

Leam
	
On 8/10/22 10:08, avi.e.gross at gmail.com wrote:
> Not sure if this question is another IQ test from someone! LOL!
> 
> Overview, once I struggled with your naming is that you have data in a
> dictionary format and a list of such items. You want to convert each
> dictionary to an object of Class Person and then instead of a list of Person
> objects want to make a dictionary of Person objects as values with keys
> specific to that object. So far, seems easy enough but you have an amorphous
> question about wanting to use generators as an exercise.
> 
> Generally, a generator does not make everything at once but keeps returning
> more as it is iterated. It can return a next item or it can return a growing
> item, so what exactly is your deliverable here? Do you want a generator that
> makes one Person at a time as needed, or one dictionary containing a person
> with a key at a time, or a growing dictionary of such dictionaries that is
> lengthened by one each time?
> 
> As a start, I  just want to make a suggestion so your code is a tad easier
> to understand.
> 
> Your make_person() function does not make A person but a list of objects of
> class Person. Consider naming it make_persons() to indicate that. Yes, it
> uses a generator expression and arguably makes one at a time. But the result
> from outside seems more naturally, to me, to be a generator that makes
> persons.
> 
> Your uses of the name "peeps" took a while to make sense and now seems to be
> a slang way of saying "peoples" and may be intuitively obvious to you but
> made me start thinking of other things to do than read your uncommented code
> that made me have to figure out what it was you were doing.
> 
> You seem to want to make a dictionary of People as values indexed by first
> name. First names tend to not be unique.  So not an optimal key unless you
> don't care or have some guarantees.
> 
> But if I am getting your question, and I bet I am not, you want to know if
> there is a briefer or simpler way to consolidate what you are doing. Will
> this work?
> 
> def make_peeps(data):
>      return { datum.get('fname', 'missing'): Person(datum) for datum in data
> }
> 
> The above just needs your list of dictionaries, stored in "data" and uses a
> dictionary comprehension to make the entire dictionary of Person objects you
> seem to want. But are you requiring this be done in some kind of generator
> for a practical reason or just as an exercise?
> 
> One obvious way to do it is with a generator function with an explicit
> yield. Put your loop in there and yield whatever you want until done. Or do
> you insist on using a generator expression way?
> 
> 
> 
> -----Original Message-----
> From: Tutor <tutor-bounces+avi.e.gross=gmail.com at python.org> On Behalf Of
> Leam Hall
> Sent: Wednesday, August 10, 2022 7:33 AM
> To: python tutor <Tutor at python.org>
> Subject: [Tutor] Playing with generators
> 
> I'm wondering if there's a way to combine "make_person" with the generator
> in "for fname, peep in". Even if it can be done, should it be done? Or would
> the code be overly complex?
> 
> The goal is to parse a group of data, and create a dict where the value is
> an object created from the data, and the key is an attribute of the object
> itself.
> 
> 
> class Person():
>       def __init__(self, data = {}):
>           self.fname = data.get('fname', 'fred')
>           self.lname = data.get('lname', 'frank')
> 
> data = [
>       { 'fname':'Wilbur', 'lname':'Lefron' },
>       { 'fname':'Al', 'lname':'Lefron' },
>       { 'fname':'Jo', 'lname':'Franco' },
>       { 'fname':'Mon', 'lname':'Pascal' },
>       { 'fname':'Gray', 'lname':'Webb-Marston'},
>       ]
> 
> def make_person(data):
>       ps = ( Person(d) for d in data)
>       return ps
>           
> peeps = {}
> 
> for fname, peep in ( (p.fname, p) for p in make_person(data) ):
>       peeps[fname] = peep
> 
> 
> for person in peeps.values():
>       print(person.lname)
> 

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