JSL question: Update missing column entries from another column

[#1]

Hi all,

I need to update missing column entries in a data table, with entries from another older column. Using JSL code, and on JMP 14.

Here is the code I am trying to work, but it keeps on throwing error "attempting to assign to an object... L-value access.."

Any help will be appreciated..

dt=current data table();
Newcols={ "anew", "bnew", "cnew"};
oldcols={ "a", "b", "c"};
		
		
//---Update entries from old cols if new column entry is missing
For( k = 1 , k <= Length( oldcols ), k++,
				
		
		For Each Row(
			temp = column(dt, Newcols[k]); 
			oldc = column(dt, oldcols[k]);
			column (dt,Newcols[k]) = If( Is Missing( as column(dt,Newcols[k]) ) , oldc , temp) ;
			);
	);

[#2]

One option would be to use << Set Each Value()

Names Default To Here(1);

dt = New Table("Untitled",
	Add Rows(4),
	New Column("a", Numeric, "Continuous", Format("Best", 12), Set Values([1, 2, 3, 4])),
	New Column("b", Numeric, "Continuous", Format("Best", 12), Set Values([5, 6, 7, 8])),
	New Column("a2", Numeric, "Continuous", Format("Best", 12), Set Values([11, ., 33, 44])),
	New Column("b2", Numeric, "Continuous", Format("Best", 12), Set Values([., ., 77, .]))
);

wait(2); // demo purposes

new_cols = {"a2", "b2"};
old_cols = {"a", "b"};

For(i = 1, i <= N Items(old_cols), i++,
	Column(dt, new_cols[i]) << Set Each Value(
		If(Is Missing(AsColumn(Column(dt, new_cols[i]))),
			AsColumn(Column(dt, old_cols[i]))
		,
			AsColumn(Column(dt, new_cols[i]))
		)
	)
);

I think you have to provide Column with [] or [Row()] if you want to add values like you suggested

For(k = 1, k <= Length(old_cols), k++,
	For Each Row(
		new_col_val = Column(dt, new_cols[k])[];
		old_col_val = Column(dt, old_cols[k])[];
		Column(dt, new_cols[k])[] = If(Is Missing(new_col_val), old_col_val, new_col_val)
	)
);

or use As Column

For(k = 1, k <= Length(old_cols), k++,
	For Each Row(
		new_col_val = AsColumn(dt, new_cols[k]);
		old_col_val = AsColumn(dt, old_cols[k]);
		AsColumn(dt, new_cols[k])[] = If(Is Missing(new_col_val), old_col_val, new_col_val)
	)
);

[#3]

Many Thanks, this worked !