Format Date-Time Values and Subset Data

JMP provides a number of date formats that you can use to make comparisons and then subset data based on the date.

Select Where Using Dates.jsl applies the Date MDY format to a column of departure dates and subsets the data. A summary table of mean net costs by departure date then appears (图 17.2).

/*  How can you work with dates in JSL? JMP provides a number of formats

that you can use to make comparisons and then subset data based on the date.

*/

hdt = Open( "$SAMPLE_DATA/Travel Costs.jmp" );

/* Apply the Date MDY format to Departure Date values and then select only

February dates. */

hdt << Select Where(

		(Date MDY( 02, 01, 2007 ) <= :Departure Date < Date MDY( 03, 1, 2007 ))

		);

/* Subset the selected rows into two tables: one table contains February

departure dates, the other contains all data for those departure dates. */

nt1 = hdt << Subset( Columns( :Departure Date ),

	Output Table Name( "February Departure Date" ) );

nt2 = hdt << Subset( Output Table Name( "February Data" ) );

/* Create a summary table, grouping mean cost by day of week that departure

took place. */

sumDt = nt2 << Summary(

	Group( :Departure Day of Week ),

	Mean( :Net Cost ),

	Output Table Name( "Mean Net Cost by Departure Date" )

);

Figure 17.2 The Original Table and the Final Summary Table 

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