Power Query column based on conditionals - if-statement

Question

Hey guys new to Power BI here and I am having some trouble creating a column based on conditionals in Power Query.
I am trying to do something like if the previous letter was A,B,or C and the current letter is E,F,or G mark True, else False.
My code looks like this so far:
Custom Column =
IF List.Contains({“A”, “B”,”C”}), [PrevLetter]
AND list.Contains({“E”, “F”, ”G”}) , [Letters]
THEN “TRUE”
ELSE “FALSE”
Output would be so something like:
PrevLetter
Letter
CustomColumn
A
F
True
X
M
False
B
E
True
C
F
True
Any help is truly appreciated!

Answer 1

The answer depends on if you are looking for a letter within a word, or if that letter represents the entire text, but for your example, one answer could be
= if Text.PositionOfAny([PrevLetter], {"A", "B","C"})+Text.PositionOfAny([Letter], {"E", "F","G"})=0 then true else false
or if you want to plan around nulls
= try if Text.PositionOfAny([PrevLetter], {"A", "B","C"})+Text.PositionOfAny([Letter], {"E", "F","G"})=0 then true else false otherwise false
or
= Table.AddColumn(Source, "Custom", each if List.ContainsAny({[PrevLetter]},{"A","B","C"}) and List.ContainsAny({[Letter]},{"D","E","F"}) then true else false )