How can I have different color for each bar of stack barplots? in R

Question

My question maybe very simple but I couldn't find the answer! I have a matrix with 12 entries and I made a stack barplot with barplot function in R. With this code:

    mydata <- matrix(nrow=2,ncol=6, rbind(sample(1:12, replace=T)))

    barplot(mydata, xlim=c(0,25),horiz=T, 
    legend.text = c("A","B","C","D","E","F"),
col=c("blue","green"),axisnames = T, main="Stack barplot")

Here is the image from the code:

What I want to do is to give each of the group (A:F , only the blue part) a different color but I couldn't add more than two color.

and I also would like to know how can I start the plot from x=2 instead of 0. I know it's possible to choose the range of x by using xlim=c(2,25) but when I choose that part of my bars are out of range and I get picture like this:

What I want is to ignore the part of bars that are smaller than 2 and start the x-axis from two and show the rest of bars instead of put them out of range.

Thank you in advance,

Answer 1

I'm not entirely sure if this is what you're looking for: 'A' has two values (x1 and x2), but your legend seems to hint otherwise.

Here is a way to approach what you want with ggplot. First we set up the data.frame (required for ggplot):

set.seed(1)
df <- data.frame(
  name = letters[1:6],
  x1=sample(1:6, replace=T),
                 x2=sample(1:6, replace=T))

  name x1 x2
1    a  5  3
2    b  3  5
3    c  5  6
4    d  3  2
5    e  5  4
6    f  6  1                 

Next, ggplot requires it to be in a long format:

# Make it into ggplot format
require(dplyr); require(reshape2)
df <- df %>%
  melt(id.vars="name")

   name variable value
1     a       x1     5
2     b       x1     3
3     c       x1     5
4     d       x1     3
5     e       x1     5
6     f       x1     6
...

Now, as you want some bars to be a different colour, we need to give them an alternate name so that we can assign their colour manually.

df <- df %>%
  mutate(variable=ifelse(
    name %in% c("b", "d", "f") & variable == "x1",
    "highlight_x1",
    as.character(variable)))

   name     variable value
1     a           x1     2
2     b highlight_x1     3
3     c           x1     4
4     d highlight_x1     6
5     e           x1     2
6     f highlight_x1     6
7     a           x2     6
8     b           x2     4
...

Next, we build the plot. This uses the standard colours:

require(ggplot2)
p <- ggplot(data=df, aes(y=value, x=name, fill=factor(variable))) + 
  geom_bar(stat="identity", colour="black") +
  theme_bw() +
  coord_flip(ylim=c(1,10)) # Zooms in on y = c(2,12)

Note that I use coord_flip (which in turn calls coord_cartesian) with the ylim=c(1,10) parameter to 'zoom in' on the data. It doesn't remove the data, it just ignores it (unlike setting the limits in the scale). Now, if you manually specify the colours:

p +  scale_fill_manual(values = c(
    "x1"="coral3",
    "x2"="chartreuse3",
    "highlight_x1"="cornflowerblue"))

Answer 2

As already mentioned in the other post is entirely clear your desired output. Here another option using ggplot2. I think the difficulty here is to reshape2 the data, then the plot step is straightforwardly.

library(reshape2)
library(ggplot2)

## Set a seed to make your data reproducible
set.seed(1)
mydata <- matrix(nrow=2,ncol=6, rbind(sample(1:12, replace=T)))

## tranfsorm you matrix to names data.frame
myData <- setNames(as.data.frame(mydata),LETTERS[1:6])
## put the data in the long format 
dd <- melt(t(myData))
## transform the fill variable to the desired behavior.
## I used cumsum to bes sure to have a unique value for all VAR2==2. 
## maybe you should chyange this step if you want an alternate behvior 
## ( see other solution)
dd <- transform(dd,Var2 =ifelse(Var2==1,cumsum(Var2)+2,Var2))
## a simple bar plot
ggplot(dd) +
  ## use stat identity since you want to set the y aes
  geom_bar(aes(x=Var1,fill=factor(Var2),y=value),stat='identity') +
  ## horizontal rotation and zooming
  coord_flip(ylim = c(2, max(dd$value)*2)) +
  theme_bw()

Another option using lattice package

I like the formula notation in lattice and its flexibility for flipping coordinates for example:

library(lattice)

barchart(Var1~value,groups=Var2,data=dd,stack=TRUE,
         auto.key = list(space = "right"),
         prepanel = function(x,y, ...) { 
           list(xlim = c(2, 2*max(x, na.rm = TRUE))) 
         })

Answer 3

You do this by using the "add" and "offset" arguments to barplot(), along with setting axes and axisnames FALSE to avoid double-plotting: (I'm throwing in my color-blind color palette, as I'm red-green color-blind)

# Conservative 8-color palette adapted for color blindness, with first color = "black".
# Wong, Bang. "Points of view: Color blindness." nature methods 8.6 (2011): 441-441.
colorBlind.8 <- c(black="#000000", orange="#E69F00", skyblue="#56B4E9", bluegreen="#009E73",
    yellow="#F0E442", blue="#0072B2", reddish="#D55E00", purplish="#CC79A7")
mydata <- matrix(nrow=2,ncol=6, rbind(sample(1:12, replace=T)))
cols <- colorBlind.8[1:ncol(mydata)]
bar2col <- colorBlind.8[8]
barplot(mydata[1,], xlim=c(0,25), horiz=T, col=cols, axisnames=T,
    legend.text=c("A","B","C","D","E","F"), main="Stack barplot")
barplot(mydata[2,], offset=mydata[1,], add=T, axes=F, axisnames=F, horiz=T, col=bar2col)

For the second part of your question, the "offset" argument is used for the first set of bars also, and you change xlim and use xaxp to adjust the x-axis numbering, and of course you must also adjust the height of the first row of bars to remove the excess offset:

offset <- 2
h <- mydata[1,] - offset
h[h < 0] <- 0
barplot(h, offset=offset, xlim=c(offset,25), xaxp=c(offset,24,11), horiz=T, 
    legend.text=c("A","B","C","D","E","F"),
    col=cols, axisnames=T, main="Stack barplot")
barplot(mydata[2,], offset=offset+h, add=T, axes=F, axisnames=F, horiz=T, col=bar2col)

Answer 4

I would like to simplify the proposed solution by @tedtoal, which was the finest one for me.

I wanted to create a barplot with different colors for each bar, without the need to use ggplot or lettuce.

 color_range<- c(black="#000000", orange="#E69F00", skyblue="#56B4E9", bluegreen="#009E73",yellow="#F0E442", blue="#0072B2", reddish="#D55E00", purplish="#CC79A7")


barplot(c(1,6,2,6,1), col= color_range[1:length(c(1,6,2,6,1))])