I have a collections groupBy filter map reduce challenge I c kotlinlang #announcements

I have a collections groupBy / filter / map / reduce challenge I can't quite get right. Can anyone help? I think I might be trying to do to much in a single line of code: given:

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allTags [
			tag { category: "genre", value: "classical", count=0, multiple=false },
			tag { category: "genre", value: "jazz",, count=0, multiple=false },
			tag { category: "composer", value: "mahler", count=0, multiple=false },
			tag { category: "composer", value: "bach", count=0, multiple=false },
			tag { category: "genre", value: "classical", count=0, multiple=false },
			tag { category: "composer", value: "bach", count=0, multiple=false },
	]

I want:

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groupedList [
			tag { category: "genre", value: "classical", count=2, multiple=true },
			tag { category: "genre", value: "jazz", count=1, multiple=false },
			tag { category: "composer", value: "mahler", count=1, multiple=false }
			tag { category: "composer", value: "bach", count=2, multiple=true }
	]
// TODO: this isn't counting correctly
val groupedList = allTags.groupBy { it.label }.values.map { it.reduce { acc, item -> Tag(category = item.category, label = item.label, url =  item.url, postCount = item.postCount++, hasPosts = item.postCount > 1) } }

spand

03/22/2020, 10:14 AM

There is no label in your objects

But it seems you need to group by category, value then map each list to the wanted value (seems simpler than using reduce)

v79

03/22/2020, 12:30 PM

Sorry, label=value. I keep changing the model.

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