Unpivot Monthly Data with a Formula

Patrick2788 

My current feeling is that both thunks and MAKEARRAY need to be approached with a certain degree of caution.  In the present instance, I decided to use concatenated strings to hold information relating to an item within the crosstab.  The code to the point of getting a list of packed records is the same whether I go on to use HSTACK or MAKEARRAY

= LET(
    packed,   nBravo&","&dates&"|"&rBravo,
    mask,     LEFT(dates,1)<>"Q",
    filtered, FILTER(packed,mask),
    list,     TOCOL(filtered),
    Unpackλ(list)
  )

Using HSTACK

UnpackHSλ = LAMBDA(list,
    LET(
        dimensions, TEXTBEFORE(list, "|"),
        d₁,  TEXTBEFORE(dimensions, ","),
        d₂,  TEXTAFTER(dimensions, ","),
        val, VALUE(TEXTAFTER(list, "|")),
        HSTACK(d₁, d₂, val)
    )
);

and using MAKEARRAY

UnpackMAλ = LAMBDA(list,
    MAKEARRAY(ROWS(list),3,
        LAMBDA(r, f,
            LET(
                item, INDEX(list, r),
                SWITCH(f,
                    1,TEXTBEFORE(TEXTBEFORE(item, "|"), ","),
                    2,TEXTAFTER(TEXTBEFORE(item, "|"), ","),
                    3,VALUE(TEXTAFTER(item, "|"))
                )
            )
        )
    )
);

(I do not do 'concise'!)

A key point of interest is that the solution with HSTACK took 10ms to refresh whereas MAKEARRAY took 690ms. That is a massive difference.