ggplot2, color segment of geom_segment

Question

I'm working on a rather elaborate plot of some indoor and outdoor activities, and I'm kinda stuck. I want to add colorize the minutes spent indoor/outdoor by (Xmin, Ymin, and Zmin) in the geom_segment step of my plot (see below). It's currently colored by only Zmin (used a continuous variable, which is kinda off).

I've pasted all the code in case others want to build something like this, I was initially inspired by this blog post.

Any help would be appreciated, thanks!

df <- data.frame(
  date = seq(Sys.Date(), len= 156, by="4 day")[sample(156, 26)],
  action = paste('Then', LETTERS[1:13], 'happed, which was not related to', LETTERS[14:26]),
  IndoorOutdoor = rep(c(-1,1), 13),
  Xmin = sample(90, 26, replace = T),
  Ymin = sample(90, 26, replace = T),
  Zmin = sample(90, 26, replace = T)
)

df$XYZmin <- rowSums(df[,c("Xmin", "Ymin", "Zmin")])*df$IndoorOutdoor

# install.packages("ggplot2", dependencies = TRUE)
require(ggplot2)

# step 1 
plot <- ggplot(df,aes(x=date,y=0))

# step 2, this is where I want to add 'more' color 
plot <- plot + geom_segment(aes(y=0,yend=XYZmin,xend=date, colour= Zmin))

# The text is added as follows
plot <- plot + geom_text(aes(y=XYZmin,label=paste(action, '\n this happed on ', date)),size=2.5,hjust=-.01, vjust=-.01, angle = 35)

# points at the end of the line segments
plot <- plot + geom_point(aes(y=XYZmin))

# #raw a vertical line
plot <- plot + geom_hline(y=0,size=1,color='purple')

#drawing the actual arrow
# plot <- plot + geom_segment(x=2011.4,xend=2012.2,y=.2,yend=0,color='purple',size=1) + geom_segment(x=2011.4,xend=2012.2,y=-.2,yend=0,color='purple',size=1)

plot <- plot + theme(axis.text.y = element_blank()) + ylab('') + xlab('')
plot + labs(title = "Timeline for when what happened")

Answer 1

Here are two approaches. One constructs each line out of different geom_segments (I think this is closer to what you were doing?) the other just uses geom_bar, which would be my preference (much more scaleable). I think there is an error when you build your data.frame - you create 56 rows when you make IndoorOutdoor, which makes problems later. I've changed that below.

set.seed(1234)
df <- data.frame(
  date = seq(Sys.Date(), len= 156, by="4 day")[sample(156, 26)],
  action = paste('Then', LETTERS[1:13], 'happed, which was not related to', LETTERS[14:26]),
  IndoorOutdoor = rep(c(-1,1), 13), #Change so there are only 26 rows
  Xmin = sample(90, 26, replace = T),
  Ymin = sample(90, 26, replace = T),
  Zmin = sample(90, 26, replace = T)
)

df$XYZmin <- rowSums(df[,c("Xmin", "Ymin", "Zmin")])*df$IndoorOutdoor
df[,8:10] <- df[,4:6]*df[,3] #Adding the sign to each X/Y/Z
names(df)[8:10] <- paste0(names(df)[4:6],"p") #to differentiate from your X/Y/Z
require(ggplot2)

For the geom_bar solution I then melt df so that a single value can be plotted, and fill mapped to the varialbe (Xmin etc)

df.m <- melt(df[,c(1:3,7:10)], measure.vars=c("Xminp", "Yminp", "Zminp"))
plot.alt <- ggplot(df.m, aes(date, value, fill=variable)) + 
  geom_bar(position="stack", stat="identity", width=0.5) + #width is just to make it look like yours
#All of this is from your original plot
  geom_text(aes(y=XYZmin,label=paste(action, '\n this happed on ', date)),size=2.5,hjust=-.01, vjust=-.01, angle = 35) + 

  geom_point(aes(y=XYZmin), show_guide=FALSE) +
  geom_hline(y=0,size=1,color='purple') +
  theme(axis.text.y = element_blank()) + ylab('') + xlab('') +
  labs(title = "Timeline for when what happened")
plot.alt

Alternatively, here is a way to build it up using geom_segment:

plot <- ggplot(df,aes(x=date)) +
#Three geom_segments 
  geom_segment(aes(y=0,yend=Xminp,xend=date), colour= "blue") +
  geom_segment(aes(y=Xminp,yend=Xminp + Yminp,xend=date), colour= "red") +
  geom_segment(aes(y=Xminp + Yminp,yend=Xminp + Yminp + Zminp,xend=date), colour= "green") +
#This is all from your plot
  geom_text(aes(y=XYZmin,label=paste(action, '\n this happed on ', date)),size=2.5,hjust=-.01, vjust=-.01, angle = 35) +
  geom_point(aes(y=XYZmin)) +
  geom_hline(y=0,size=1,color='purple') +
  theme(axis.text.y = element_blank()) + ylab('') + xlab('') +
  labs(title = "Timeline for when what happened")
plot

Hope that makes sense... let me know if it's not what you were after.