Adding Custom Colors to Plotly Bar Chart with ColorRamp

Question

I am using Plotly to make charts and graphs. Currently I am trying to apply a custom color to my graph, but the graph has more colors than the ColorBrewer palette offers.

Here is my data: https://github.com/kffont/Colorado/blob/master/data1.csv

The data is the min, median and max of 5 number summaries for 15 rows of data. The 16th row identifies the categorical labels (min, med, max).

I used Color Ramp to create a function to allow more colors to be used in my bar plot. That is working fine. The problem occurs when I try and assign the colors to the plot. I've used many solutions to no avail. Here are some of the methods I've tried:

1. create a vector of colnames, color = colnames colors = color palette

2. Assign colors with palettename[1] etc using indexing

3. remove the traces and create 2 lines of code; 1 for the plot and one for the layout. I tried this method with and without the color/colors method in #1

Here is the base code that I've used.

#Libraries
library(plotly)
library(colorRamps)
library(RColorBrewer)

#Create palette      col.a.cat1<-colorRampPalette(brewer.pal(9,"YlOrRd"))

#Color = Colnames
abc<-colnames(data1)

#Barcharts #1 (p) and #2 (o)
p<-plot_ly(a.cat.14, x = ~Level, y = ~a.cat.14[, 1],, type = 'bar', name = colnames(a.cat.14[1])) %>%
    add_trace(y = ~a.cat.14[, 2],  name = colnames(a.cat.14[2])) %>%
      add_trace(y = ~a.cat.14[, 3], name = colnames(a.cat.14[3])) %>%
      add_trace(y = ~a.cat.14[, 4], name = colnames(a.cat.14[4])) %>%
      add_trace(y = ~a.cat.14[, 5], name = colnames(a.cat.14[5])) %>%
      add_trace(y = ~a.cat.14[, 6], name = colnames(a.cat.14[6])) %>%
      add_trace(y = ~a.cat.14[, 7], name = colnames(a.cat.14[7])) %>%
      add_trace(y = ~a.cat.14[, 8], name = colnames(a.cat.14[8])) %>%
      add_trace(y = ~a.cat.14[, 9], name = colnames(a.cat.14[9])) %>%
      add_trace(y = ~a.cat.14[, 10], name = colnames(a.cat.14[10])) %>%
      add_trace(y = ~a.cat.14[, 11], name = colnames(a.cat.14[11])) %>%
      add_trace(y = ~a.cat.14[, 12], name = colnames(a.cat.14[12])) %>%
      add_trace(y = ~a.cat.14[, 13], name = colnames(a.cat.14[13])) %>%
      add_trace(y = ~a.cat.14[, 14], name = colnames(a.cat.14[14])) %>%
      add_trace(y = ~a.cat.14[, 15], name = colnames(a.cat.14[15])) %>%
      layout(title = "Adult Cats: Minimum, Median, Maximum", yaxis = list(title= 'Count'), barmode = 'group')
p

o<-plot_ly(a.cat.14, x = ~Level, y = ~a.cat.14[, c(1:15)],  type = 'bar', name = colnames(a.cat.14)) %>%
  layout(title = "Adult Cats: Minimum, Median, Maximum", yaxis = list(title= 'Count'), barmode = 'group')

Your help is appreciated!

Answer 1

• colorRampPalette needs an 'lower' and 'upper' color, in your case probably yellow and red.

   colorRampPalette(list('yellow', 'red')) 

• When you call the returned function the provided numeric argument is the number of colors to return

   colors <- colorRampPalette(list('yellow', 'red'))(15) 

• When can then assign the colors to Plotly

   p <- plot_ly(x = x, y = y, marker = list(color = colors), type='bar') 

---

#Libraries
library(plotly)
library(colorRamps)
library(RColorBrewer)

#read csv
csv <- read.csv(url("https://raw.githubusercontent.com/kffont/Colorado/master/data1.csv"))
col_names <- colnames(csv)

#create palette      
colors <- colorRampPalette(list('yellow', 'red'))(length(col_names))

#get y values
y <- list()
for (i in 1:length(col_names))
{
  y[[i]] = csv[[i]][3]  
}

p <- plot_ly(x = col_names[2:15], y = y[2:15], marker = list(color = colors[2:15]), type='bar')
p