Looking to delete set number of rows

[#1]

Good Morning

                         Using JmP for process control and capability. Would like to be able to select only the last 20 rows (ongoing) of a table and exclude the rest, as now running to several hundred rows; the early data somewhat skewing the capability analysis due to process changes. Any help would be much appreciated, thanks.

Chris

[#2]

Might this be what you want?

Names Default To Here( 1 );
dt = Open("$SAMPLE_DATA/big class.jmp");

ex = dt << select where( Row() < N Rows( dt ) - 20 );
ex << exclude << hide;

Control Chart( Group Size( 1 ), KSigma( 3 ),
	Chart Col( :height, Individual Measurement, Moving Range ) );

[#3]

Thank you, this works perfectly, much aapreciated.

Chris

[#4]

Another way to do this...

To set up the script, run the analysis the way you want, whether its in distribution, with a control chart, capability, or process screening. Then add a local data filter to look at the date or row range you want, e.g. the last 50 rows or something.  

Then find this like in the script:

	Local Data Filter(
		Add Filter( columns( :Row ), Where( :Row >= 15 & :Row <= 20 ) )
	),

and edit it to look like this:

	Local Data Filter(
		Add Filter( columns( :Row ), Where( :Row = nrow()-5 & :Row = nrow() ) )
	),

In the first script the report uses row 15 to 20.  

the report uses the last 5 rows regardless of how many rows there are.* 

*... and yes, I konw 5 rows are two few for a good capability report, this just an example