R plotly: How to connect lines on polar/radar chart? - r

Question

I am creating a polar chart in R with plotly, but I don't want the values between lines to be filled with color. I found the line_close property for python library, but I can't find the equivalent in R.
Chart code:
library(plotly)
p <- plot_ly(
type = 'scatterpolar',
mode = 'lines',
) %>%
add_trace(
mode = 'lines',
r = c(3, 0, 1),
theta = c('A','B','C'),
name = '1'
) %>%
add_trace(
mode = 'lines',
r = c(1, 2, 3),
theta = c('A','B','C'),
name = '2'
) %>%
layout(
polar = list(
radialaxis = list(
angle = 90,
visible = T,
range = c(0,3),
showline = F,
color = '#bfbfbf',
nticks = 4,
tickangle = 90
)
)
)
p
Chart image:

Answer 1

I've had a good look through plotly::schema, and there doesn't seem to be an option to do this built in to the R port of plotly.
However, it is trivial to define your own add_closed_trace function like this:
add_closed_trace <- function(p, r, theta, ...)
{
plotly::add_trace(p, r = c(r, r[1]), theta = c(theta, theta[1]), ...)
}
You can use this as a drop-in for add_trace, like this:
library(plotly)
p <- plot_ly(
type = 'scatterpolar',
mode = 'lines',
) %>%
add_closed_trace(
mode = 'lines',
r = c(3, 0, 1),
theta = c('A','B','C'),
name = '1'
) %>%
add_closed_trace(
mode = 'lines',
r = c(1, 2, 3),
theta = c('A','B','C'),
name = '2'
) %>%
layout(
polar = list(
radialaxis = list(
angle = 90,
visible = T,
range = c(0,3),
showline = F,
color = '#bfbfbf',
nticks = 4,
tickangle = 90
)
)
)
p