topic Re: Using loops in formula in Discussions

Using loops in formula

aumair — Thu, 11 May 2017 00:16:56 GMT

Hi,

Is it possible to use loop in the column formula? For example, I have a column named TEST, and I write for (i=1, i<5, i++, :TEST=char(i)) ... but I do not get anything, that column is blank after I hit apply/OK. From the loop I am hoping to get every row in the column would be 4.

Sorry for asking such a simple question, but coluldn't find the answer by quickly going thru appendix A of "Using JMP" manual.

Thanks,
Ahmad

Re: Using loops in formula

aumair — Thu, 11 May 2017 00:30:05 GMT

No need to reply....found out the issue, thanks! Assignment should be outside the loop.

Re: Using loops in formula

gronk — Sat, 24 Oct 2020 19:43:46 GMT

Hi, I am trying to use loops in the column formula for the first time, and I seem to be running into your original problem.

Could you clarify how you solved the issue, and what you meant by the assignment should be outside the loop?

Thanks!

Re: Using loops in formula

txnelson — Sat, 24 Oct 2020 20:45:37 GMT

What is your specific issue. Can you post what formula you are currently using that isn't working for you?

Re: Using loops in formula

gronk — Sun, 25 Oct 2020 06:07:15 GMT

Thank you very much for your reply.

The final problem I'm trying to solve is the following: I have stress-strain data for multiple test strips for multiple formulations (please see the attached JMP data file). The attached table contains 4 different formulation+strip "groups" i.e) FormA/strip1, FormA/strip2, FormB/strip1, FormB/strip2... For each group, I need to identify 1) the maximum stress (tensile strength) and 2) the strain associated with the maximum stress. To identify the maximum stress, I created a column "Tensile Strength" and used simply used "Col Max()" in the Formula Editor (see image below)

Now, I'm looking to populate the "%elongation" column with the strain values associated with the maximum stress (tensile strength) for each group, and this is where my issue lies. Rather than going through the table to manually identify these strain values and populate the "%elongation" column, I'm wondering if there's a way to accomplish this with a column formula (or JSL script).

I was thinking this may involve a combination of loops and/or conditional functions.

Initially, I experimented with iterating through the "Stress" column with a for loop, to check if Stress=Tensile Strength in a given row (if yes, then populate the "%elongation" column with the associated strain value). Please see the attached JPG file "stress-strain data_jmp community help_iteration attempt" for the initial column formula/attempt. The column remained unchanged/blank.

I then tried to simply populate the first 5 rows in the "%elongation" column with the strain values in the given rows (please see the attached JPG file "stress-strain data_jmp community help_for loop"). The column remained blank, and this is what prompted my initial post. I'm assuming there are key errors in how I'm using the functions.

**Moreover, I recognize that my initial formula is far too simplistic for my final goal.

Apologies for the lengthy post and if I was unclear with anything. I'd be happy to provide any clarification. I'm quite new to JMP, thus any advice/help with this would be greatly appreciated. Thank you in advance.

Re: Using loops in formula

txnelson — Sun, 25 Oct 2020 08:46:53 GMT

Here is a formula for the creation of %elongation. It is not a very efficient formula, but it will find the value regardless of the order of the data.

curForm = :Formulation;
curStrip = :Strip;
theRow = (Current Data Table() << get rows where(
	:Formulation == curForm & :Strip == curStrip & :Stress == :Tensile Strength
))[1];
:Strain[theRow];

If the data are sorted by Formulation and Strip, then the more efficient formula below can be used.

If( Row() == 1 | :Formulation != Lag( :Formulation ) | :Strip != Lag( :Strip ),
	curForm = :Formulation;
	curStrip = :Strip;
	theRow = (Current Data Table() << get rows where(
		:Formulation == curForm & :Strip == curStrip & :Stress == :Tensile Strength
	))[1];
);
:Strain[theRow];

Re: Using loops in formula

gronk — Sun, 25 Oct 2020 17:27:22 GMT

Thanks so much for your help/response.

In regards to the simple for loop I used to try to populate the first five rows in the "%elongation" column, I'm curious why the column remains unchanged/blank. Am I completely off the mark in how I used the formula and/or defined the arguments?

In the very early stages of learning JMP and JSL, trying to learn from my mistakes.

Thanks again for the help!

Re: Using loops in formula

txnelson — Sun, 25 Oct 2020 18:14:48 GMT

I do think your current understanding of formula usage is in error. I am particularly confused with what your expected results for the formula

For( i=0, i<=5, i++, :Strain )

By default, formulas are run once for each row. Therefore, most of the time a For() loop would not be used.

I have attached a data table with 4 different formulas applied. I am hoping that if you look at the different formulas, that it will help you adjust your understanding of how formulas work.