echarts4r comes with a highly customisable grid and axis, but admittedly they take some getting used to.

## Axis helper

You can customise the axis with e_axis, e_x_axis or e_y_axis, you can see the official documentation for more details. There is also a helper function, e_format_axis and its sisters e_format_x_axis and e_format_y_axis. The latter lets you easily add suffix or prefix to your axis labels.

Say you want to plot against ceslius.

df <- data.frame(
x = 1:20, # celsius
y = runif(20, 1, 100) # percentages
)

df %>%
e_charts(x) %>%
e_line(y) %>%
e_format_x_axis(suffix = "°C") %>%
e_legend(FALSE)

Since version 0.2.1 you can also easily format the axis to decimal, percentages or currencies thanks to contribution from Artem Klevtsov.

df %>%
dplyr::mutate(y = y / 100) %>%
e_charts(x) %>%
e_line(y, legend = FALSE) %>%
e_x_axis(
formatter = e_axis_formatter("currency", currency = "GBP")
) %>%
e_y_axis(
formatter = e_axis_formatter("decimal", digits = 3)
)

## Grid

You can also customise the grid to have, for instance, multiple plots on one canvas.

Let’s initialise a basic plot.

df <- data.frame(
x = 1:20,
w = runif(20, 1, 100),
z = runif(20, 25, 75)
)

df %>%
e_charts(x) %>%
e_line(w) %>%
e_line(z)

Now say we don’t want w and z on the same plot. We could of course make two entirely different plots (2 plots initialised with e_charts()), but it would be cleaner to have them on the same canvas, a bit like ggplot2 facets.

First two plots on the same canvas means multiple axis, so we’ll plot each serie on its own axis.

echarts4r is an R API to a JavaScript library, so arrays start at one; x and y indices default to 0 so we only need to change one of the series’ indices to 1. Therefore one serie is plotted on index 0 and the other on index 1 for two xand y axis.

df %>%
e_charts(x) %>%
e_line(w) %>%
e_line(z, x_index = 1, y_index = 1)

Notice how echarts4r puts the additional axis on the top and right of the plot. This is a useful feature but not what we want; we’re missing a split grid.

We use e_grid twice for two grids, we define the height of each; 35% is ideal for stacked grids, you need some margin for the legend, the axis, etc. hence not using 50%.

df %>%
e_charts(x) %>%
e_line(w) %>%
e_line(z, x_index = 1, y_index = 1) %>%
e_grid(height = "35%") %>% # two grids of 35% height
e_grid(height = "35%", top = "50%") # this grid is 50% from the top

However, we still have both line plots on the same grid. Here is how to think about grids and axis in echarts4r.

1. Your series (i.e.: e_line) are plotted against axis (e_axis)
2. These axis are plotted in grids e_grid

So we have two grids and two axis but the axis are both plotted on the same grid(point #2 above). So we need to move our two additional axis to another grid. Note that grid indices also start at 0 here.

df %>%
e_charts(x) %>%
e_line(w) %>%
e_line(z, x_index = 1, y_index = 1) %>%
e_grid(height = "35%") %>%
e_grid(height = "35%", top = "50%") %>%
e_y_axis(gridIndex = 1) %>% # put x and y on grid index 1
e_x_axis(gridIndex = 1)

There you go!

You can also have a different grid to put the plots side by side.

df %>%
e_charts(x) %>%
e_line(w) %>%
e_line(z, x_index = 1, y_index = 1) %>%
e_grid(width = "35%") %>%
e_grid(width = "35%", left = "55%") %>%
e_y_axis(gridIndex = 1) %>% # put x and y on grid index 1
e_x_axis(gridIndex = 1)

## Why bother?

Well now those charts can share interactions.

df %>%
e_charts(x) %>%
e_line(w) %>%
e_line(z, x_index = 1, y_index = 1) %>%
e_grid(height = "35%") %>%
e_grid(height = "35%", top = "50%") %>%
e_y_axis(gridIndex = 1) %>%
e_x_axis(gridIndex = 1) %>%
e_tooltip(trigger = "axis") %>%
e_datazoom(x_index = c(0, 1)) # add data zoom for for x axis

## Axis

You can also mess with the axis to completely change your chart. For instance, from a regular bar chart:

df <- data.frame(
x = LETTERS[1:10],
y = seq(1, 20, by = 2),
z = runif(10, 5, 20)
)

df %>%
e_charts(x) %>%
e_bar(y)

to a polar chart.

df %>%
e_charts(x) %>%
e_polar() %>%
e_angle_axis(x) %>% # angle = x
e_bar(y, coord_system = "polar")

df %>%
e_charts(x) %>%
e_polar() %>%
e_angle_axis() %>%
e_bar(y, coord_system = "polar")
df %>%
e_scatter(z, coord_system = "polar")