Re: groupBy in D?
On Tue, 2017-03-14 at 16:35 +, Russel Winder wrote:
>
So by analogy with the Python code I get the following D code, but it
seems ugly compared to the niceness of the Groovy code (and equivalent
Kotlin and Ceylon codes):
import std.array: array, split;
import std.algorithm: filter, map;
import std.file: dirEntries, SpanMode;
import std.path: baseName, dirName;
import std.stdio: writeln;
import std.typecons: Tuple, tuple;
auto files = dirEntries(path, SpanMode.shallow)
.filter!(a => a.isFile)
.map!(a => a.baseName)
.map!(a => tuple(a.split('_')[0], a))
.array;
writeln(files);
string[][string] groups;
foreach (Tuple!(string, string) f; files) {
groups[f[0]] ~= [f[1]];
}
--
Russel.
=
Dr Russel Winder t: +44 20 7585 2200 voip: sip:russel.win...@ekiga.net
41 Buckmaster Roadm: +44 7770 465 077 xmpp: rus...@winder.org.uk
London SW11 1EN, UK w: www.russel.org.uk skype: russel_winder
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Re: groupBy in D?
On Tue, 2017-03-14 at 16:12 +0100, Daniel Kozak via Digitalmars-d-learn
wrote:
> […]
>
> Can you post some example? Maybe in python, kotlin whatever so I can
> better understand what you want
In my head I had something such as Groovy's
files = new File('test-data').listFiles().collect{it.name}
println files.groupBy({ it.split('_')[0]})
The I remembered that itertools.groupby in Python behaves like D's
std.algorithm.iteration.chunkBy and not like Groovy's groupBy. So in
Python you have to hack it with:
from collections import defaultdict
from os import listdir
from os.path import isfile, splitext
result = defaultdict(list)
files = tuple((item.split('_')[0], item) for item in listdir('test-data') if
isfile('test-data/' + item))
for p, v in files:
result[p] += [v]
print(result)
Given the seeming lack of Groovy-style groupBy, I guess I will have to
do something Python-like in D. Except I am not sure D has an equivalent
of defaultdict.
--
Russel.
=
Dr Russel Winder t: +44 20 7585 2200 voip: sip:russel.win...@ekiga.net
41 Buckmaster Roadm: +44 7770 465 077 xmpp: rus...@winder.org.uk
London SW11 1EN, UK w: www.russel.org.uk skype: russel_winder
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Re: groupBy in D?
Dne 14.3.2017 v 16:02 Russel Winder via Digitalmars-d-learn napsal(a): I am having a hard time Google-ing today. Pytho, Groovy, Kotlin, etc. have a "groupBy" function that takes a sequence and a key and creates a dictionary/associative array with keys the result of the key function on the sequence and key values all the items that match the key. D doesn't seem to have such a function directly. Unless I missed it… Can you post some example? Maybe in python, kotlin whatever so I can better understand what you want
groupBy in D?
I am having a hard time Google-ing today. Pytho, Groovy, Kotlin, etc. have a "groupBy" function that takes a sequence and a key and creates a dictionary/associative array with keys the result of the key function on the sequence and key values all the items that match the key. D doesn't seem to have such a function directly. Unless I missed it… -- Russel. = Dr Russel Winder t: +44 20 7585 2200 voip: sip:russel.win...@ekiga.net 41 Buckmaster Roadm: +44 7770 465 077 xmpp: rus...@winder.org.uk London SW11 1EN, UK w: www.russel.org.uk skype: russel_winder signature.asc Description: This is a digitally signed message part
