Adds an additional bubble series to the provided bubble chart. It is
preferable to provide all series upfront instead of mutating the underlying
chart. For other chart types, see the add-series! function.

Adds an XY or category series to an already existing chart. It is preferable
to provide all series upfront to avoid mutable operations on a chart.

For bubble-charts, use `add-bubble-series!`. For pie charts, just use
(.addSeries chart name val).

Converts a chart into a java.awt.image.BufferedImage.

Returns a raw bubble chart. Bubble charts are hard to make right,
so please see the tutorial for more information about how to create
one. The render-styles page will give you information about styling
options.

Different render styles for bubble series. For now this is useless, as you
can only use :round. Apparently :box is around the corner though.

Returns a category chart. See the tutorial for more information
about how to create category charts, and see the render-styles
documentation for styling options.

Returns a raw category chart. Prefer `category-chart` unless you
run into performance issues. See the tutorial for more information
about how to create category charts, and see the render-styles
documentation for styling options.

The different styles you can use for category series.

All the default java.awt colors as keywords. You can use this map
to iterate over the keys, in case you'd like to compare different
colors. Or you could use java.awt.Color directly to use the exact
color you want.

Transforms coll into a series map by using the values in the provided keymap.
There's no requirement to provide :x or :y (or any key at all, for that
matter), although that's common.

Example: (extract-series {:x f, :y g, :bubble bubble} coll)
      == {:x (map f coll), :y (map g coll), :bubble (map bubble coll)}

The different legend positions. Note that xchart implements only a
subset of inside/outside for the different positions.

All the default XChart markers as keywords. To create your own marker, you
must _subclass_ the org.knowm.xchart.style.markers.Marker class, so it's often
better to use the default ones.

The different annotation types you can use to annotate pie charts.
By default, this is :percentage.

Returns a pie chart. The series map is in this case just a mapping
from string to number. For styling information, see the
render-styles page.

Example:
(c/pie-chart {"Red" 54
              "Green" 34})

The different pie render styles. It is :pie by default.

Spits the chart to the given filename. If no type is provided, the type is
guessed by the filename extension. If no extension is found, an error is
raised.

The default stroke types provided by XChart. You can also use a self-made
stroke if you're not happy with any of the predefined ones.

The different kinds of text alignments you can use.

The different default themes you can use with xchart.

Converts a chart into a byte array.

Transforms a map of maps such that the inner keys and outer keys are flipped.
That is, `(get-in m [k1 k2])` = `(get-in (transpose-map m) [k2 k1])`. The
inner values remain the same.

Utility function to render one or more charts in a swing frame.

Returns an xy-chart. See the tutorial for more information about
how to create an xy-chart, and see the render-styles documentation
for styling options.

The different xy-render styles: :area, :scatter and :line.