The Grid form ()
plots 2-d point data aggregated into rectangular cells on the plotting plane.
You can optionally use a weighting for the points,
and you can configure how the values are combined to produce the
output pixel values (colours).
You can use this layer type in various ways,
including as a 2-d histogram or weighted density map,
or to plot gridded data.
The X and Y dimensions of the grid cells (or equivalently histogram bins) can be configured in terms of either the data coordinates or relative to the plot dimensions.
The shading is done using the shared colour map. This colour map is used by all currently visible Grid, Aux and Weighted layers. When at least one such layer is being plotted, the Aux Axis control is visible in the control panel, which allows you to configure the colour map, range, ramp display etc.
Example Grid plot
Grid form configuration panel
The configuration options are:
sum
) but not others (e.g. mean
).
count
or sum
.
However, if there is a non-blank Weight coordinate,
one of the other values such as mean
may be more revealing.
The following options (some are more useful than others) are currently available:
sum
: the sum of all weightsmean
: the mean of all weightsmedian
: the median of all weights;
(note, this is more expensive to calculate and can be slow)min
: the minimum weightmax
: the maximum weightstdev
: the sample standard deviation of all weightscount
: the number of points plotted
(weight value is ignored, this is like Density mode)hit
: one if any point is plotted, blank otherwise
(weight value is ignored, this is like Flat mode)