Highlight a single “bar” in ggplot

Question

i\'d like to choose colors and fill patterns for individual bars in a bar graph (Highlight a single \"bar\")

The bars, that i\'d like to fill in another color are \"

Answer 1

scale_fill_manual should work. Create a column in your data that indicates whether the bar should be highlighted or not, then feed that column to the fill aesthetic. scale_fill_manual can then be used to assign colors as desired. Here's a representative example:

library( tidyverse )
library( ggplot2 )

## Generate some data to plot
X <- mtcars %>% group_by( cyl ) %>% summarize( mpg = mean(mpg) ) %>% ungroup

## Add a column indicating whether the category should be highlighted
X <- X %>% mutate( ToHighlight = ifelse( cyl == 6, "yes", "no" ) )

## Data looks like this
## A tibble: 3 x 3
##    cyl      mpg ToHighlight
##  <dbl>    <dbl>       <chr>
##1     4 26.66364          no
##2     6 19.74286         yes
##3     8 15.10000          no

## Plot the data
ggplot( X, aes( x = cyl, y = mpg, fill = ToHighlight ) ) +
    geom_bar( stat = "identity" ) +
    scale_fill_manual( values = c( "yes"="tomato", "no"="gray" ), guide = FALSE )

Note guide = FALSE that hides the legend associated with the ToHighlight column.