In a compute program, how would I calculate in Kotlin where the values of a list are all equal to ea...

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[therealbluepandabear]

In a compute program, how would I calculate in Kotlin where the values of a list are all equal to each to each other? Thank you.

[Endre Deak]

convert the list to set and check if the size of the set is 1. Assuming that the items in the list are 1) similar type 2) comparable to each other

[Endre Deak]

(or call .distinct() with the same assumptions)

[ephemient]

another option (will short circuit unlike the above): list.all { it == list.first() }

[nanodeath]

this is a fun codegolf question. I think you could also do something like .asSequence().zipWithNext().any { a, b -> a != b }

[therealbluepandabear]

@ephemient would this code work:

[therealbluepandabear]

fun numbersEven(data: List<Int>) = data.toSet().size == 1

[nanodeath]

works fine, it's just not the most efficient

[ephemient]

given your description I would expect empty to be true, and it doesn't match the function name... but yes, it does something

[therealbluepandabear]

@ephemient oh yes.. I will rename this function.

[nanodeath]

oh, another idea -- data.asSequence().distinct().take(2).toList().size == 1

[therealbluepandabear]

@nanodeath thanks for this.

[ephemient]

why not .all though? I do mean it, that if the contract is "all values of a list are equal to each other", it should be vacuously true for the empty list

[therealbluepandabear]

@ephemient I have this other question. Is there a way to do this code in a lambda-like way... Instead of looping over and printing words which start with 'z' can we do this in a couple of lines using lambdas? Here is my current code

for (string in asList) {
    if (string != asList[asList.size - 1]) {
        if (string[0] == 'Z' || string[0] == 'z') {
            println(string)
        }
    }
}

Apologise if this is a strange question... again, I feel like there is more concise kotlin-like way of doing this

[therealbluepandabear]

apologies if this question is a bit strange. I am Just getting to know Kotlin.

[therealbluepandabear]

@ephemient wait never mind Kotlin suggested this for me:

asList
    .asSequence()
    .filter { it != asList[asList.size - 1] && (it[0] == 'Z' || it[0] == 'z') }
    .forEach { println(it) }

[ephemient]

not really Kotlin, just general coding...

for (string in asList) {
    if (string != asList.last() && string.isNotEmpty() && string.first() in "Zz") {
        println(string)
    }
}

if you wanted to do it with the Kotlin collections extensions, you could certainly

asList.filter { string -> string != asList.last && string.firstOrNull()?.let("Zz"::contains) == true }.forEach(::println)

[ephemient]

unless you can guarantee your strings are all non-empty, I would use .firstOrNull() because [0] will crash on an empty string

[therealbluepandabear]

@ephemient I think this is alright?

asList
    .filter { it.isNotEmpty() && (it[0] == 'Z' || it[0] == 'z') }
    .forEach { println(it) }

[ephemient]

sure, although you've lost the != last check

[therealbluepandabear]

@ephemient what do you mean by this

[ephemient]

your previous code contained if (string != asList[asList.size - 1])

[ephemient]

which can be simplified to string != asList.last()

[therealbluepandabear]

@ephemient Oh ok... will do this instead.