Apply the supplied grouping to an array.
Array_Type grpdata = grpGetGroupSum( Array_Type dataArray, Array_Type
grouping )
This function applies the grouping information from
the grouping parameter to the dataArray parameter.
The return value is an array whose length equals
that of the input data (the dataArray argument)
and each element within a group contains the same value.
As an example,
grpGetGroupSum( [1,2,3,4,5,6], [1,-1,1,-1,1,1] )
will return the array
since the groups consist of the first two elements,
then the next two elements, with the last two elements
being un-grouped.
chips> ysum = grpGetGroupSum( y, grp )
The ysum array will contain the data from the y array
after the grouping scheme stored in the grp array
is applied to it. The ysum array will have the
same size as the y array. The following code shows
you how you can convert ysum into an array in
which each element corresponds to one group.
chips> i = where( grp == 1 )
chips> ygrp = ysum[i]
Here we created an array i whose elements correspond
to those elements in the grp array with a value of 1
(this marks the start of a group). The ygrp array is
then created by using this array to extract the
corresponding elements from the ysum array.
It could have been written in one line as:
chips> ygrp = ysum[ where( grp == 1 ) ]
chips> x = [0.5:6.0:0.05]
chips> y = 3 + 30 * exp( - (x-2.0)^2 / 0.1 )
chips> ( grp, qual ) = grpNumCounts( y, 15 )
chips> ysum = grpGetGroupSum( y, grp )
chips> nchan = grpGetChansPerGroup( grp )
chips> i = where( grp == 1 and qual == 0 )
chips> xstart = x[i]
chips> yavg = ysum[i] / nchan[i]
Here we take the function
y = 3 + 30 * exp( -(x-2)^2 / 0.1 )
and group it by 15 counts per group.
We then filter the summed array (ysum) so that it
corresponds to only those elements at the start
of a group - the
condition - and for which the quality flag is "good" -
which is given by
This array is divided by the number of elements in each
group to calculate the average value in the group.
Note that the xstart array gives the start position of each
group.
- group
-
grpadaptive,
grpadaptivesnr,
grpbin,
grpbinfile,
grpbinwidth,
grpgetchanspergroup,
grpgetgroupsum,
grpgetgrpnum,
grpmaxslope,
grpminslope,
grpnumbins,
grpnumcounts,
grpsnr
- modules
-
group
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