This post is an introduction to the `circlize`

package: the ultimate way to build circular charts with R. It shows how to initialize a circular section and fill it with a scatterplot.

In R, circular plots are made using the `circlize`

package. Circular plots are composed by several regions (8 here), each representing a level of a factor. Three steps are required to build a circular plot:

*Step 1*: Initialize the chart with`circos.initialize()`

. Provide the factor vector, and the numeric values to use for the X axis. The circle will be split in as many zone as the number of levels present in your factor. Each region will be as long as the coresponding x axis.*Step2*: Build the regions with`circos.trackPlotRegion()`

. You have to specify the factors once again, and tell what to use for the Y axis if needed.*Step3*: Add a chart in each region. Here`circos.trackPoints()`

is used to build a scatterplot. See chart #226 for other chart types.

```
# Upload library
library(circlize)
# Create data
data = data.frame(
factor = sample(letters[1:8], 1000, replace = TRUE),
x = rnorm(1000),
y = runif(1000)
)
# Step1: Initialise the chart giving factor and x-axis.
circos.initialize( factors=data$factor, x=data$x )
# Step 2: Build the regions.
circos.trackPlotRegion(factors = data$factor, y = data$y, panel.fun = function(x, y) {
circos.axis()
})
# Step 3: Add points
circos.trackPoints(data$factor, data$x, data$y, col = "blue", pch = 16, cex = 0.5)
```