topic Re: How to SUM rows with variable column names? in Discussions

How to SUM rows with variable column names?

rleeper — Fri, 10 Oct 2014 15:15:20 GMT

I have a table with a variable number of columns. I want to add a column that SUM's all of the columns in a row no matter how many / few appear.

I tried this:

TotRow = Trans << Get Column Names(Numeric);

TR = N Items(TotRow);

Trans << New Column( "Total Time",

Numeric);

For Each Row(:Total Time[]=Sum(Column(TotRow[1::TR])[]));

But it only SUMS the first row and not the rest. The number of columns and rows are always variable week to week.

Re: How to SUM rows with variable column names?

ian_jmp — Fri, 10 Oct 2014 15:31:01 GMT

If you want to sum all numeric columns, and you don't need a formula column, you could do:

NamesDefaultToHere(1);

// Make a table to work with

nr = 10;

nc = 3;

dt = NewTable("Some Continuous Data");

For(c=1, c<=nc, c++,

dt << NewColumn("Col "||Char(c), Numeric, Continuous, Formula(RandomInteger(1, 10)));

);

dt << AddRows(nr);

// Get the data into a matrix

mat = dt << GetAsMatrix;

// Get the sum of each row

sumVec = (VSum(mat`))`;

// Add the sum column

dt << NewColumn("Sum", Numeric, Continuous, Values(sumVec));

Note JSL does not have an 'HSum()' so you need to transpose and then transpose back.

Re: How to SUM rows with variable column names?

rleeper — Fri, 10 Oct 2014 15:45:45 GMT

Ian,

Thanks that worked perfectly!

Re: How to SUM rows with variable column names?

rleeper — Fri, 10 Oct 2014 19:38:46 GMT

Ian,

It is great to have the answer, it is better to understand the answer.

In this statement:

sumVec = (VSum(mat`))`;

What are the ` for? I understand the VSum statement, just not why ` is needed on either side of it.

Re: How to SUM rows with variable column names?

Jeff_Perkinson — Fri, 10 Oct 2014 20:27:17 GMT

That's the matrix transpose operator. It's a postfix operator, so it works on the argument to its left.

As Ian@JMP said, since JMP doesn't have an HSum() you have to use VSum() on the transposed matrix and then transpose it back.

-Jeff

Re: How to SUM rows with variable column names?

rleeper — Mon, 13 Oct 2014 11:48:54 GMT

Jeff,

Thank you for the answer, and especially the link. Any day I learn something new is a good day.