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In general terms the axes on which the graphics are plotted are
defined by the datasets you have selected.
The axis labels are set from the column names or expressions chosen
for the Main dataset, and the ranges are determined
so that all the data from the chosen datasets can be seen.
However, these things can be adjusted manually.
The following features are available directly from the window for
configuring axis range:
-
X-Y Zoom
- In some of the windows
(2d scatter plot,
histogram and
density map),
you can change both axis ranges by zooming in or out
with the mouse on the plot surface itself.
To zoom in, place the mouse at the top left of the
region you want to examine, press the button, drag it to the
bottom right corner, and release the button. To zoom out, drag
up and left instead.
A box is drawn as you drag so you can see what you're doing.
-
Axis Zoom
- In some of the windows
(2d scatter plot,
histogram,
density map,
stacked lines)
you can modify the range on each axis independently by dragging the
mouse over where the axis is drawn. The 'active region' for dragging
is just below the X axis and just to the left of the Y axis, in the
region where the numeric and text labels are written.
When the pointer is in one of these regions, the mouse cursor
symbol changes to indicate that zooming can be done.
As for the X-Y Zoom, drag left-to-right or up-to-down
to zoom in and right-to-left or down-to-up to zoom out.
-
Centre Zoom
- The spherical plot allows you to zoom
in on the central part of the window. The 'active region' for
dragging is to the right of the plot, where the legend is shown.
When the pointer is in this region, the mouse cursor symbol changes
to indicate that zooming can be done.
Drag down to zoom in and up to zoom out.
-
Rescale
- If you find you're zoomed to a region you don't want to be in,
you can use the Rescale toolbar button to return to the default
scale (full coverage).
Some windows may have per-axis rescale buttons too
(
,
).
For more control over axis range and labelling, use the
Configure Axes (
) toolbar button,
which will pop up a dialogue like the following:
Axis Configuration Dialogue for 2-d axes
You can fill in these values as follows:
-
Label
- For each axis the label box contains the text used to annotate
the axis in the plot. By default this is the same as the text
in the Main dataset column selector
(usually a column name), followed by the units if known.
However, you can change it by typing whatever text you like.
-
Range
- The range boxes allow you to specify the lower and upper limits
of each axis. By default these are blank, meaning that the plot
will size its axes so that all the data can be seen. However, if
you fill in one or both of the boxes with a suitable numeric value,
the lower/upper bound will be fixed at that. Note that the lower
bound (left box) must be numerically less than the upper bound
(right box).
Both values are reset if the plot's axis is changed (a new column or
expression is selected for the Main dataset), or if the range is
reset in some other way (e.g. by zooming).
Next Previous Up Contents
Next: Defining Subsets by Region
Up: Common Features
Previous: Dataset Selectors
TOPCAT - Tool for OPerations on Catalogues And Tables
Starlink User Note
253
TOPCAT web page:
http://www.starlink.ac.uk/topcat/
Author email:
m.b.taylor@bristol.ac.uk