How to create a new column in a data table from a list of column values using conditional statements?

rk2 — Tue, 21 May 2024 20:52:44 GMT

I want to check values in two numeric columns within a data table. Now I have these two numeric columns' names in a list. I use a for loop to iterate through the list of these chosen numeric column names, then i want to check against a threshold value (say 100). Then I want to create a new column and put labels accordingly - either label "A" or "B" - depending on the given columns in the data table.

Let's say these are the two numeric columns:

numeric_col_1 = {100, 200, 250, 700}

numeric_col_2 = {200, 250, 500, 100}

And the threshold is 100.

Now the labeled columns pseudocode I want to implement is as follows:

labeled_col = (if numeric_col > 100, "A", "B");

So the labeled columns will now show:

labeled_col_1 = {"B", "A", "A", "A"};

labeled_col_2 = {"A", "A", "A", "B"};

Here is some example code:

concat_dt = datatable("concatenated");
new_val_list = {"num_col1", "num_col2"};
name_list = {"col1", "col2"};
stop = nitems(new_val_list);
for (i = 1, i <=stop, i++,
	col_name = name_list[i] || "_Label_A_B";
	show(col_name);
	concat_dt << New Column( col_name,
		Character,
		"Nominal",
		Formula( If( Column(concat_dt, new_val_list[i]) > 200, "A", "B" ) )
	)	
);

But the above code only shows empty columns even though they have been created with their respective column names in the data table.

Re: How to create a new column in a data table from a list of column values using conditional statements?

txnelson — Tue, 21 May 2024 21:25:47 GMT

Use As Column() instead of Column()

concat_dt = datatable("concatenated");new_val_list = {"num_col1", "num_col2"};name_list = {"col1", "col2"};stop = nitems(new_val_list);
for (i = 1, i <=stop, i++,
	col_name = name_list[i] || "_Label_A_B";
	show(col_name);
	concat_dt << New Column( col_name,
		Character,
		"Nominal",
		Formula( If( As Column(concat_dt, new_val_list[i]) > 200, "A", "B" ) )
	)	
);

However, I believe this is a better solution

Names Default To Here( 1 );
concat_dt = Data Table( "concatenated" );
name_list = {"col1", "col2"};

For Each( {col, i}, name_list,
	concat_dt << New Column( "num_" || col || "_Label_A_B" ,
		Character,
		"Nominal",
		Set Each Value( If( As Column( concat_dt, col ) > 200, "A", "B" ) )
	);
);

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How to create a new column in a data table from a list of column values using conditional statements?

Re: How to create a new column in a data table from a list of column values using conditional statements?