topic Re: log2 transformation using new formula column in Discussions

log2 transformation using new formula column

rexneal — Tue, 17 Dec 2019 15:08:48 GMT

How can I log2 transformation many columns (hundreds) all at once? Is there a way of doing log2 transformation using the new formula column?
Thanks, Neal

Re: log2 transformation using new formula column

Mark_Bailey — Tue, 17 Dec 2019 15:15:44 GMT

I don't think so. The log base 2 is not a built-in function. As far as I know, you would have to use the equivalent log( x ) / log( 2 ) expression.

It is possible to define custom functions that can appear in the formula editor. I do not think that they appear in the New Column Formula menu, though. There are a lot of Community members who are smarter than me, so someone else might have a better answer for you.

Re: log2 transformation using new formula column

Dan_Obermiller — Tue, 17 Dec 2019 17:33:46 GMT

So, you do have to build the formula, but it may not be as bad as you think. Let's suppose you have 100 columns where you need this transformation. Put those columns all together. By this I mean, they are contiguous. Suppose the first one is Column 11, second one is Column 12, etc. up to Column 110. Now create 100 new columns. Select your 100 new columns and choose Cols > Standardize Attributes. In the Standardize Properties area click on Column Properties and select Formula.Check the box for Substitute Column Reference. Click Edit Formula. Now enter the first formula for your first new column. With my scenario it would be Log(Column 111)/Log(2). When you click OK JMP will fill in a formula for every one of your new columns, marching through each of the columns that had the data to be transformed. Your last formula column should be Log(Column 110)/Log(2).

Re: log2 transformation using new formula column

jules — Tue, 17 Dec 2019 20:50:27 GMT

Hi @rexneal,

I would suggest something similar to @Dan_Obermiller, but by first taking advantage of the New Formula Column functionality you do have to make new columns and title them correctly.

Select your columns
Right Click column header > New Formula Column > Transform > Log
Select the new Log transformed columns
Right Click column header > Standardize Attributes
In the Standardize Properties section, select Formula
Check the box for Substitute Column Reference
Click Edit Formula
Select the column inside the log function, and click the comma key to reveal the base
Change the base to 2, click ok to close the formula, then ok to close Standardize Attributes.

It might sound like a lot, but you can do this in 45 seconds. Here's a short video showing all the steps.

(view in My Videos)

I hope this helps!

@jules

Re: log2 transformation using new formula column

rexneal — Tue, 14 Jan 2020 13:07:50 GMT

Thanks so much. Neal