ggplot Box plots side by side

Question

I would like side by side box plots (total and ELISA) by media type. I saw in other chats that I need to melt the data. When I do this I get the following

Error: stat_boxplot requires the following missing aesthetics: y

My data:

media    total    ELISA  
surface     1.3     2.7
surface     5.2     6.5
surface     0.9     2.9
surface     0.7     2.1
porewater   376.8   651.0
porewater   288.7   308.0
porewater   32.3    63.3
porewater   69.7    184.0
porewater   116.0   11.4
porewater   31.6    51.5
porewater   38.6    97.5
porewater   63.2    152.0
porewater   118.0   254.0
porewater   1147.5  4174.0
porewater   626.6   798.0
porewater   39.2    81.8
porewater   3.3     7.5
porewater   70.3    231.5
porewater   1.7     3.2
sediment    567.0   1454.1
sediment    24.0    70.7
sediment    13.7    23.9
sediment    16.9    105.7
sediment    39.7    5.9
sediment    8.2     17.6
sediment    27.4    85.0
sediment    14.7    30.8

My code:

library(reshape2)
elisa.m <- melt(elisa, media.vars='media', measure.vars=c('total','ELISA'))

library(ggplot2)
p <- ggplot(elisa.m) +
  geom_boxplot(aes(x = media, y=value)) + 
  stat_boxplot(geom = "errorbar", width = 0.5)

I'm not sure why this isn't working. Should I be naming it something other than value?

Answer 1

Your mapping aes() should be within ggplot() for stat_boxplot to inherit it. Therefore,

  p <- ggplot(elisa.m, aes(x = media, y = value)) +
  geom_boxplot() + 
  stat_boxplot(geom = "errorbar", width = 0.5)

Answer 2

myplot = ggplot(elisa.m, aes(x=media, y=measurement))+
          geom_boxplot()+
          stat_boxplot(geom ='errorbar', width=0.5) +  
          facet_rep_wrap(~mode, repeat.tick.labels=TRUE)

However, for this to be working, you must reorganize your data so you have the following format:

media   measurement  mode
surface    1.3       total
  .                  total
  .                  total
surface    2.7       elisa
  .                  elisa
  .                  elisa

Hope it helps :) Ana