Defaultdict is what i would expect from a language that strives to be elegant. Groupby is horrible unless i use multiple comprehensions to get what i expect for a grouping: a Dictionary/Map. How did they come up with returning lists of tuples ???
did someone notice that there is no Maria under physics field in scientists_by_field5 snippet? This is because the iterable for itertools.groupby() must be sorted to produce correct result. You can also make it more readable by unpacking groupby() result inside of the dictionary comprehension scientists_by_field5 = { k : list(map(lambda x: x.name, g)) for k, g in itertools.groupby(sorted(scientists, key=lambda x: x.field), lambda x: x.field) }
Hey Dan, As always, great video. Would you please do consider video on search, trees and linked list in future please. I found lot of sources but they are very hard to understand in programming way. Thank you.
In your final version of the reduce function implementation you wrote this line: lambda acc, val: {**acc, **{val.field: acc[val.field] + [val.name]}}, ... When you could do this: lambda acc, val: {**acc, val.field: acc[val.field] + [val.name]}, ... Am I missing something?
My attempt to get scientists_by_field using lambda: reduce(lambda acc, val: (acc[val.field].append(val), acc)[1], scientists, defaultdict(list)) I think it's more readable and it should be faster than Dan's solution, since every iteration creates 1 tuple and updates existing dictionary, while he creates 2 new dictionaries. I wish I came up with upacking solution tho.
Look at this solution with empty dict and lambda function : scientist_by_field = reduce( lambda acc, val: acc[val.field].append(val.name) if val.field in acc else acc.update({val.field:[val.name,]}) or acc, scientists, {} )
The defaultdict tip was awesome!
Thanks for the kind words!
Defaultdict is what i would expect from a language that strives to be elegant. Groupby is horrible unless i use multiple comprehensions to get what i expect for a grouping: a Dictionary/Map. How did they come up with returning lists of tuples ???
did someone notice that there is no Maria under physics field in scientists_by_field5 snippet? This is because the iterable for itertools.groupby() must be sorted to produce correct result. You can also make it more readable by unpacking groupby() result inside of the dictionary comprehension
scientists_by_field5 = { k : list(map(lambda x: x.name, g)) for k, g in itertools.groupby(sorted(scientists, key=lambda x: x.field), lambda x: x.field) }
I absolutely loved this! The examples and the explanation were on point. You got a new subs, thanks for sharing!
Thank you for putting **readability** above shorter lines (code-fu)
how did you add autocomplete to your python interpreter??
yes i was wondering too
Thank you for making this!
tonnes of great stuff in this playlist. Thank You!
Hey Dan,
As always, great video. Would you please do consider video on search, trees and linked list in future please. I found lot of sources but they are very hard to understand in programming way. Thank you.
Glad you liked it. Thanks for the suggestion! :-)
In your final version of the reduce function implementation you wrote this line:
lambda acc, val: {**acc, **{val.field: acc[val.field] + [val.name]}}, ...
When you could do this:
lambda acc, val: {**acc, val.field: acc[val.field] + [val.name]}, ...
Am I missing something?
Could you please explain final reduce() version.
My attempt to get scientists_by_field using lambda:
reduce(lambda acc, val: (acc[val.field].append(val), acc)[1], scientists, defaultdict(list))
I think it's more readable and it should be faster than Dan's solution, since every iteration creates 1 tuple and updates existing dictionary, while he creates 2 new dictionaries. I wish I came up with upacking solution tho.
Nice one! Thanks for sharing your solution with us :)
Iterable doesn't have to be a sequence, and reduce docs are explicit that you need a sequence not any iterable. This is not the inconsistency.
This guy is awesome
what tools are you using to develop? the intellisense you get is so clean.
Here is a list of resources I use dbader.org/resources/
I made these changes to the code in my end.
from functools import reduce
instead of val['age'], I had to use val.age. Only then it worked
Can you add this list here?
Oh that took me a few minutes to sink in how that works.
I hope the video helped clear it up for you!
What is this Python REPL?
To be honest I prefer the reduce() version over the "pythonic" version.
Look at this solution with empty dict and lambda function :
scientist_by_field = reduce(
lambda acc, val: acc[val.field].append(val.name) if val.field in acc else acc.update({val.field:[val.name,]}) or acc,
scientists,
{}
)
Excellent.
Glad you liked it!
The defaultdict is basically the opposite of functional programming paradigm 😅 Even more dynamic than usual 🤣 But good to know