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Legends in R

How to modify the legend in R graphs. Nine examples of how to move, color, and hide the legend.


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Legend Names

library(plotly)
library(tidyr)
library(plyr)

data <- spread(Orange, Tree, circumference)
data <- rename(data, c("1" = "Tree1", "2" = "Tree2", "3" = "Tree3", "4" = "Tree4", "5" = "Tree5"))

fig <- plot_ly(data, x = ~age, y = ~Tree1, type = 'scatter', mode = 'lines', name = 'Tree 1')
fig <- fig %>% add_trace(y = ~Tree2, name = 'Tree 2')
fig <- fig %>% add_trace(y = ~Tree3, name = 'Tree 3')
fig <- fig %>% add_trace(y = ~Tree4, name = 'Tree 4')
fig <- fig %>% add_trace(y = ~Tree5, name = 'Tree 5')

fig

Hiding the Legend

library(plotly)
library(tidyr)
library(plyr)

data <- spread(Orange, Tree, circumference)
data <- rename(data, c("1" = "Tree1", "2" = "Tree2", "3" = "Tree3", "4" = "Tree4", "5" = "Tree5"))

fig <- plot_ly(data, x = ~age, y = ~Tree1, type = 'scatter', mode = 'lines')
fig <- fig %>% add_trace(y = ~Tree2)
fig <- fig %>% add_trace(y = ~Tree3)
fig <- fig %>% add_trace(y = ~Tree4)
fig <- fig %>% add_trace(y = ~Tree5)
fig <- fig %>% layout(showlegend = FALSE)

fig

Hiding Legend Entries

library(plotly)
library(tidyr)
library(plyr)

data <- spread(Orange, Tree, circumference)
data <- rename(data, c("1" = "Tree1", "2" = "Tree2", "3" = "Tree3", "4" = "Tree4", "5" = "Tree5"))

fig <- plot_ly(data, x = ~age, y = ~Tree1, type = 'scatter', mode = 'lines', name = 'Tree 1')
fig <- fig %>% add_trace(y = ~Tree2, name = 'Tree 2')
fig <- fig %>% add_trace(y = ~Tree3, name = 'Tree 3', showlegend = FALSE)
fig <- fig %>% add_trace(y = ~Tree4, name = 'Tree 4')
fig <- fig %>% add_trace(y = ~Tree5, name = 'Tree 5')

fig

Positioning the Legend Inside the Plot

library(plotly)
library(tidyr)
library(plyr)

data <- spread(Orange, Tree, circumference)
data <- rename(data, c("1" = "Tree1", "2" = "Tree2", "3" = "Tree3", "4" = "Tree4", "5" = "Tree5"))

fig <- plot_ly(data, x = ~age, y = ~Tree1, type = 'scatter', mode = 'lines', name = 'Tree 1')
fig <- fig %>% add_trace(y = ~Tree2, name = 'Tree 2')
fig <- fig %>% add_trace(y = ~Tree3, name = 'Tree 3')
fig <- fig %>% add_trace(y = ~Tree4, name = 'Tree 4')
fig <- fig %>% add_trace(y = ~Tree5, name = 'Tree 5')
fig <- fig %>% layout(legend = list(x = 0.1, y = 0.9))

fig

Positioning the Legend Outside the Plot

library(plotly)
library(tidyr)
library(plyr)

data <- spread(Orange, Tree, circumference)
data <- rename(data, c("1" = "Tree1", "2" = "Tree2", "3" = "Tree3", "4" = "Tree4", "5" = "Tree5"))

fig <- plot_ly(data, x = ~age, y = ~Tree1, type = 'scatter', mode = 'lines', name = 'Tree 1')
fig <- fig %>% add_trace(y = ~Tree2, name = 'Tree 2')
fig <- fig %>% add_trace(y = ~Tree3, name = 'Tree 3')
fig <- fig %>% add_trace(y = ~Tree4, name = 'Tree 4')
fig <- fig %>% add_trace(y = ~Tree5, name = 'Tree 5')
fig <- fig %>% layout(legend = list(x = 100, y = 0.5))

fig

Changing the Legend Orientation

library(plotly)
library(tidyr)
library(plyr)

data <- spread(Orange, Tree, circumference)
data <- rename(data, c("1" = "Tree1", "2" = "Tree2", "3" = "Tree3", "4" = "Tree4", "5" = "Tree5"))

fig <- plot_ly(data, x = ~age, y = ~Tree1, type = 'scatter', mode = 'lines', name = 'Tree 1')
fig <- fig %>% add_trace(y = ~Tree2, name = 'Tree 2')
fig <- fig %>% add_trace(y = ~Tree3, name = 'Tree 3')
fig <- fig %>% add_trace(y = ~Tree4, name = 'Tree 4')
fig <- fig %>% add_trace(y = ~Tree5, name = 'Tree 5')
fig <- fig %>% layout(legend = list(orientation = 'h'))

fig

Styling the Legend

library(plotly)
library(tidyr)
library(plyr)

data <- spread(Orange, Tree, circumference)
data <- rename(data, c("1" = "Tree1", "2" = "Tree2", "3" = "Tree3", "4" = "Tree4", "5" = "Tree5"))

l <- list(
  font = list(
    family = "sans-serif",
    size = 12,
    color = "#000"),
  bgcolor = "#E2E2E2",
  bordercolor = "#FFFFFF",
  borderwidth = 2)


fig <- plot_ly(data, x = ~age, y = ~Tree1, type = 'scatter', mode = 'lines', name = 'Tree 1')
fig <- fig %>% add_trace(y = ~Tree2, name = 'Tree 2')
fig <- fig %>% add_trace(y = ~Tree3, name = 'Tree 3')
fig <- fig %>% add_trace(y = ~Tree4, name = 'Tree 4')
fig <- fig %>% add_trace(y = ~Tree5, name = 'Tree 5')
fig <- fig %>% layout(legend = l)

fig

Size of Legend Items

In this example, since the itemsizing attribute is set to constant, the size of legend items symbols remains the same, regardless of how tiny/huge the bubbles are in the graph.

library(plotly)

fig <- plot_ly(
  type='scatter',
  x=c(1, 2, 3, 4, 5),
  y=c(1, 2, 3, 4, 5),
  mode='markers',
  marker=list(size=10))

fig <- fig %>% add_trace(
  type='scatter',
  x=c(1, 2, 3, 4, 5),
  y=c(5, 4, 3, 2, 1),
  mode='markers',
  marker=list(size=100))

fig <- fig %>% layout(legend= list(itemsizing='constant'))
fig

Legend Title

library(plotly)

fig <- plot_ly(
  type='scatter',
  mode='line',
  x=c(1, 2, 3, 4, 5),
  y=c(1, 2, 3, 4, 5),
  name="Increasing"
)

fig <- fig %>% add_trace(
  type='scatter',
  mode='line',
  x=c(1, 2, 3, 4, 5),
  y=c(5, 4, 3, 2, 1),
  name="Decreasing"
) 

fig <- fig %>% layout(legend=list(title=list(text='<b> Trend </b>')))
fig

Grouped Legend

Plotly legends are interactive. Click on the legend entries to hide and show traces. The legendgroup key groups legend entries so that clicking on one legend entry will hide or show all of the traces in that group.

library(plotly)
library(tidyr)
library(plyr)

data <- spread(Orange, Tree, circumference)
data <- rename(data, c("1" = "Tree1", "2" = "Tree2", "3" = "Tree3", "4" = "Tree4", "5" = "Tree5"))

fig <- plot_ly(data, x = ~age, y = ~Tree1, type = 'scatter', mode = 'lines',
        legendgroup = 'group1', name = 'Zone 1 - Tree 1')
fig <- fig %>% add_trace(y = ~Tree2, legendgroup = 'group2', name = 'Zone 2 - Tree 1')
fig <- fig %>% add_trace(y = ~Tree3, legendgroup = 'group1', name = 'Zone 1 - Tree 2')
fig <- fig %>% add_trace(y = ~Tree4, legendgroup = 'group2', name = 'Zone 2 - Tree 2')
fig <- fig %>% add_trace(y = ~Tree5, legendgroup = 'group1', name = 'Zone 1 - Tree 3')

fig

Subplot Grouped Legend

library(plotly)

df <- data.frame(x = c("a","b","c"), y = c(2,3,2), y2 = c(4,2,4))

fig1 <- df
fig1 <- fig1 %>% plot_ly(
    type = 'bar', 
    x = ~x, 
    y = ~y, 
    color = ~x, 
    legendgroup = ~x
  )
fig1 <- fig1 %>% layout(
    xaxis = list(
      showgrid = F
    ),
    yaxis = list(
      showgrid = F
    )
  )

fig2 <- df
fig2 <- fig2 %>% plot_ly(
    type = 'bar', 
    x = ~x, 
    y = ~y2, 
    color =  ~x, 
    legendgroup = ~x, 
    showlegend = F
  )
fig2 <- fig2 %>% layout(
    xaxis = list(
      showgrid = F
    ),
    yaxis = list(
      showgrid = F
    )
  )

fig <- subplot(fig1, fig2, nrows = 2, shareX = T)

fig

Reference

See https://plotly.com/r/reference/#layout-legend for more information and chart attribute options!

What About Dash?

Dash for R is an open-source framework for building analytical applications, with no Javascript required, and it is tightly integrated with the Plotly graphing library.

Learn about how to install Dash for R at https://dashr.plot.ly/installation.

Everywhere in this page that you see fig, you can display the same figure in a Dash for R application by passing it to the figure argument of the Graph component from the built-in dashCoreComponents package like this:

library(plotly)

fig <- plot_ly() 
# fig <- fig %>% add_trace( ... )
# fig <- fig %>% layout( ... ) 

library(dash)
library(dashCoreComponents)
library(dashHtmlComponents)

app <- Dash$new()
app$layout(
    htmlDiv(
        list(
            dccGraph(figure=fig) 
        )
     )
)

app$run_server(debug=TRUE, dev_tools_hot_reload=FALSE)