Circos > Documentation > Tutorials > Ideograms > Variable Radius

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3 — Drawing Ideograms

8. Variable Radius

By default, every ideogram is placed at the same radial position. This is controlled by the radius parameter within the <ideogram> block (conventionally found in ideogram.conf).

radius = 0.85r

The value is relative to the image radius.

You can place individual ideograms at different radial positions by using the chromosomes_radius parameter in the root of the configuration tree.

chromosomes_radius = hs1:0.5r;hs2:0.55r;hs3:0.6r;hs4:0.65r;hs5:0.7r;hs6:0.75r;hs7:0.8r;hs8:0.85r;hs9:0.9r;hs10:0.95r

The radial position values in this parameter are relative to the default ideogram radius, defined by radius in the <ideogram> block.

For example, if the image radius is 1500p and the default ideogram radius is 0.9r, then all ideograms are at 1350 pixels (1500×0.9) from the center. Now, if chromosomes_radius further specifies hs1:0.5r, then hs1 will appear at 675 pixels from the center (1500×0.9×0.5).

Once the radial position of an ideogram has been redefined using chromosomes_radius, all features associated with that ideogram (plots, links, text, etc) will be automatically relocated to match the new ideogram position. In other words, you do not need to remember that specific ideograms may be at different positions.

setting radius for tagged ideograms

If you've tagged your ideograms when creating regions,

chromosomes = hs1[a]:0-50;hs1[b]:150-);hs2[c]:0-50;hs2[d]:150-);hs3[e]

then adjusting the radius of any region can be done by using the tag

chromosomes_radius = hs1:0.8r;a:0.9r;d:0.8r

The radius values will be processed in order, with subsequent radius values overriding previous ones. For example, each region of hs1 will be set to 0.8r, but the region tagged by a will be 0.9r.

suppressing ticks and tick labels

When decreasing the radius of an ideogram you may find that the ticks and their labels crowd together. In these cases, it is useful to use the tick_separation and label_separation parameters in the <ticks> block to define the minimum distance between ticks and their labels.