SUBARRAYS

[tboulden]

This LAMBDA provides a recursive loop to extract subarrays of given set of dimensions, or warns the user if their provided dimension(s) are bigger than their target array; I am returning the list of the subarrays using ARRAYTOTEXT, but this could be substituted with another function to suit the purpose of the user (i.e. if getting sums of each subarray, etc.)

Uses List.Combine

=LAMBDA(arr,r,c,
    LET(
        m,ROWS(arr),
        n,COLUMNS(arr),
        IF(OR(r>m,c>n),"User dimension exceeds array dimension",
            LET(
                rCt,(m-r+1),
                cCt,(n-c+1),
                subArrCt,rCt*cCt,
                LoopTraverseArr,
                    LAMBDA(self,i,stopCt,
                        LET(
                            current,
                                INDEX(
                                    arr,
                                    SEQUENCE(r,1,1+QUOTIENT(i-1,cCt),1),
                                    SEQUENCE(1,c,1+MOD(i-1,cCt),1)
                                ),
                            value,ARRAYTOTEXT(current,1),
                            return,
                                IF(
                                    i<stopCt,self(self,i+1,stopCt),
                                    value
                                ),
                            IF(
                                i=stopCt,return,
                                List.Combine(value,return)
                            )
                        )
                    ),
                LoopTraverseArr(LoopTraverseArr,1,subArrCt)
            )
        )
    )
)

LAMBDA_Subarrays.xlsx
	A	B	C	D	E	F	G
1		3 x 4					2 x 1
2		A	B	C	D		{"A";"E"}
3		E	F	G	H		{"B";"F"}
4		I	J	K	L		{"C";"G"}
5							{"D";"H"}
6							{"E";"I"}
7							{"F";"J"}
8							{"G";"K"}
9							{"H";"L"}
10
11							3 x 3
12							{"A","B","C";"E","F","G";"I","J","K"}
13							{"B","C","D";"F","G","H";"J","K","L"}
14
15							3 x 5
16							User dimension exceeds array dimension
17
Subarrays

Cell Formulas
Range	Formula
B2:E4	B2	=CHAR(SEQUENCE(3,4,65,1))
G2:G9	G2	=LAMBDA(arr,r,c, LET( m,ROWS(arr), n,COLUMNS(arr), IF(OR(r>m,c>n),"User dimension exceeds array dimension", LET( rCt,(m-r+1), cCt,(n-c+1), subArrCt,rCt*cCt, LoopTraverseArr, LAMBDA(self,i,stopCt, LET( current,INDEX(arr,SEQUENCE(r,1,1+QUOTIENT(i-1,cCt),1),SEQUENCE(1,c,1+MOD(i-1,cCt),1)), value,ARRAYTOTEXT(current,1), return, IF( i<stopCt,self(self,i+1,stopCt), value ), IF( i=stopCt,return, List.Combine(value,return) ) ) ), LoopTraverseArr(LoopTraverseArr,1,subArrCt) ) ) ) )(B2#,2,1)
G12:G13	G12	=SubArrays(B2#,3,3)
G16	G16	=SubArrays(B2#,3,5)
Dynamic array formulas.

 

[tboulden]

Recursion limits were making this impractical for larger dimension arrays to extract smaller dimension subarrays, so I derived a non-recursive analogue. There is a trade-off though as you can no longer perform operations on the individual subarrays in the LAMBDA, have to pick your methodology based on use case.

=LAMBDA(arr,r,c,
    LET(
        m,ROWS(arr),
        n,COLUMNS(arr),
        IF(OR(r>m,c>n),"User dimension exceeds array dimension",
            LET(
                rCt,(m-r+1),
                cCt,(n-c+1),
                subArrCt,rCt*cCt,
                irCt,subArrCt,
                icCt,r*c,
                rIndex,1+INT(SEQUENCE(irCt,icCt,0,1)/(cCt*icCt))+TRANSPOSE(INT(SEQUENCE(icCt,irCt,1/((irCt*c)+1),1/((irCt*c))))),
                cIndex,1+MOD(SEQUENCE(irCt,icCt,0,1),c)+MOD(SEQUENCE(irCt,1,0,1),cCt),
                INDEX(arr,rIndex,cIndex)
            )
        )
    )
)