Categorical column in to a dummy array in Excel - excel

Question

I'm trying to translate a machine-learning model into excel, so that data analysts could play with it interactively.
I'd like to transform a categorical variable into dummy representation:
WeekDay
Monday
Thursday
to
WeekDay
{1,0,0,0,0,0,0}
{0,0,0,1,0,0,0}
Using excel arrays.
I tried this:
={INT(A1="Monday"),INT(A1="Tuesday"),INT(A1="Wednesday"), ...}
However, for some reason, excel doesn't accept forumlas in array expressions.
This approach does work, but it is problematic - since it does not allow combinig multiple arrays into one
=IF(A1="Monday", {1,0,0,0,0,0,0}, IF(A1="Tuesday", {0,1,0,0,0,0,0}, ....))
Also, it's super ugly
Any ideas ?

Answer 1

To get your array you can use INDEX like this:
INDEX(IF(TEXT(ROW($2:$8),"dddd")=A1,1,0),0)
This returns a vertical array.
to return a horizontal array use:
INDEX(IF(TEXT(COLUMN($B:$H),"dddd")=A2,1,0),0)
I have spilled the results of the array in the photo below:
If one has the Dynamic Array Formula SEQUENCE the ROW and COLUMN can be replaced with:
SEQUENCE(7,,2)
and
SEQUENCE(,7,2)
Respectively

Answer 2

I am not sure what the end goal is, but I would suggest instead of an array (again, assuming you are not utilizing VBA, and even if you are, this is very possible with Case functions):
Use the formula =Weekday(Cell,different return type for which day should = 1)
If you were to use the actual date (e.g. 5/1/2020), display it through custom formatting with only the day of the week (typically data analysis will already have the full date),
Cell Value A20 = "5/1/2020", format display Long Date - "Friday, May 1, 2020"
cell referencing with formula '=WEEKDAY(A20,1)' = 6
cell referencing with formula '=WEEKDAY(A20,2)' = 5 (is this similar to {0,0,0,0,1,0,0} enough for you to use?)
if using VBA, you could define a range with logic to turn this into {0,0,0,0,1,0,0}
Hope this helps.