Compare an element from a map with the rest of the map - scala

Question

I'm trying to select the last element from a map and compare it against the other last elements in the map to say if the selected element is higher or lower.
So far I can get it to select the element from user input but cannot work out how to loop through the map and get it to compare against the other elements:
def menu(f: (String) => (String, Int)) = {
print("Number > ")
val data = f(readLine)
println(s"${data._1}: ${data._2}")
}
Here is the map which the elements are coming from:
val mapdata = Map(
"A1" -> List(9, 7, 2, 0, 0, 2, 7, 9, 1, 2, 4, 1, 9, 6, 5, 3, 2, 3, 7, 2, 8, 5, 4, 5, 1, 6, 5, 2, 4, 1),
"B2" -> List(0, 7, 6, 3, 3, 3, 1, 2, 9, 2, 9, 7, 4, 7, 3, 6, 3, 9, 5, 2, 9, 7, 3, 4, 6, 3, 4, 3, 4, 1),
"C3" -> List(8, 7, 1, 8, 0, 5, 8, 0, 5, 9, 7, 5, 3, 7, 9, 8, 1, 4, 6, 5, 6, 6, 3, 6, 8, 8, 7, 4, 0, 6),
"D4" -> List(2, 9, 5, 7, 3, 8, 6, 9, 7, 9, 0, 1, 3, 1, 3, 0, 0, 1, 3, 8, 5, 4, 0, 9, 7, 1, 4, 5, 2, 9),
"E5" -> List(2, 6, 8, 0, 3, 5, 2, 1, 5, 9, 4, 5, 3, 5, 5, 8, 8, 2, 5, 9, 3, 8, 6, 7, 8, 7, 4, 1, 2, 3),
"F6" -> List(2, 7, 5, 9, 1, 9, 2, 4, 1, 6, 3, 7, 4, 3, 4, 5, 9, 2, 2, 4, 8, 7, 9, 2, 2, 7, 9, 1, 6, 9),
"G7" -> List(6, 9, 5, 0, 8, 0, 0, 5, 8, 5, 8, 7, 1, 6, 6, 1, 5, 2, 2, 7, 9, 5, 5, 9, 1, 4, 4, 0, 2, 0),
"H8" -> List(2, 8, 8, 3, 2, 1, 1, 8, 5, 9, 0, 2, 1, 6, 9, 7, 9, 6, 7, 7, 0, 9, 5, 2, 5, 0, 2, 1, 8, 6),
"I9" -> List(2, 1, 8, 2, 4, 4, 2, 4, 9, 4, 0, 6, 9, 5, 9, 4, 9, 1, 8, 6, 3, 4, 4, 3, 7, 9, 1, 2, 6, 6)
)
for example I select H8 and its last element is 6
I then want to compare it to all last elements and say if it is higher or lower than each of the last elements.
Thanks in advance

Answer 1

I'm not sure if I understand you correctly. You can access last element of the list by calling last.
object A extends App {
val mapdata: Map[String, List[Int]] = Map(
"A1" -> List(9, 7, 2, 0, 0, 2, 7, 9, 1, 2, 4, 1, 9, 6, 5, 3, 2, 3, 7, 2, 8, 5, 4, 5, 1, 6, 5, 2, 4, 1),
"B2" -> List(0, 7, 6, 3, 3, 3, 1, 2, 9, 2, 9, 7, 4, 7, 3, 6, 3, 9, 5, 2, 9, 7, 3, 4, 6, 3, 4, 3, 4, 1),
"C3" -> List(8, 7, 1, 8, 0, 5, 8, 0, 5, 9, 7, 5, 3, 7, 9, 8, 1, 4, 6, 5, 6, 6, 3, 6, 8, 8, 7, 4, 0, 6),
"D4" -> List(2, 9, 5, 7, 3, 8, 6, 9, 7, 9, 0, 1, 3, 1, 3, 0, 0, 1, 3, 8, 5, 4, 0, 9, 7, 1, 4, 5, 2, 9),
"E5" -> List(2, 6, 8, 0, 3, 5, 2, 1, 5, 9, 4, 5, 3, 5, 5, 8, 8, 2, 5, 9, 3, 8, 6, 7, 8, 7, 4, 1, 2, 3),
"F6" -> List(2, 7, 5, 9, 1, 9, 2, 4, 1, 6, 3, 7, 4, 3, 4, 5, 9, 2, 2, 4, 8, 7, 9, 2, 2, 7, 9, 1, 6, 9),
"G7" -> List(6, 9, 5, 0, 8, 0, 0, 5, 8, 5, 8, 7, 1, 6, 6, 1, 5, 2, 2, 7, 9, 5, 5, 9, 1, 4, 4, 0, 2, 0),
"H8" -> List(2, 8, 8, 3, 2, 1, 1, 8, 5, 9, 0, 2, 1, 6, 9, 7, 9, 6, 7, 7, 0, 9, 5, 2, 5, 0, 2, 1, 8, 6),
"I9" -> List(2, 1, 8, 2, 4, 4, 2, 4, 9, 4, 0, 6, 9, 5, 9, 4, 9, 1, 8, 6, 3, 4, 4, 3, 7, 9, 1, 2, 6, 6)
)
val choice = "H8"
val numberToBeCompared = mapdata.getOrElse(choice, throw new RuntimeException(s"couldn't find $choice")).last
mapdata.filter(_._1 != choice)
.values
.foreach(list => {
if (list.last > numberToBeCompared)
println(s"${list.last} > $numberToBeCompared")
else
println(s"${list.last} <= $numberToBeCompared")
})
}
Result:
1 <= 6
1 <= 6
0 <= 6
3 <= 6
9 > 6
9 > 6
6 <= 6
6 <= 6
Is this what you need ?
Note that I still learn Scala so there's probably better way of doing this.
I also don't know if any list in mapdata can be empty so use Option if necessary.
// EDIT
If you want the letters you may try sth like this:
val choice = "H8"
val numberToBeCompared = mapdata.getOrElse(choice, throw new RuntimeException(s"couldn't find $choice")).last
mapdata.filter(_._1 != choice)
.foreach(entry => {
if (entry._2.last > numberToBeCompared)
println(s"${choice} > ${entry._1}")
else
println(s"${choice} <= ${entry._1}")
})
H8 <= A1
H8 <= B2
H8 <= G7
H8 <= E5
H8 > D4
H8 > F6
H8 <= C3
H8 <= I9
You just need to remember that when you iterate through mapdata you get entry. entry._1 is the key (your string), entry._2 is the list.