adjust y-axis for missings in ggplot2? - r

Question

First some toy data:
df = read.table(text =
"id year value sex
1 2000 0 1
1 2001 1 0
1 2002 0 1
1 2003 0 0
2 2000 0 0
2 2002 0 0
2 2003 1 0
3 2002 0 1
4 2000 0 0
4 2001 0 1
4 2002 1 0
4 2003 0 1 ", sep = "", header = TRUE)
When I want to visualize year by id for sex==1, I do
df2 <- df[df$sex==1,]
p <- ggplot(df2, aes(y=id))
p <- p + geom_point(aes(x=year))
p
How can I hide observation 2 from the graph so that the distance between each remaining id's is the same? Is there a general way how to adjust the distance between two ticks on the y-axis when my breaks are id?
Does the solution also works when using facets?
p <- ggplot(df, aes(y=id))
p <- p + geom_point(aes(x=year))
p <- p + facet_grid(sex ~.)

Answer 1

Edited based on OP's clarification
Create individual plots and use the gridExtra package.
I am not sure if this is what you are looking for, but the use of reorder() should help.
Just to test it out, I changed the "id" value of 4 to be 7 in your toy dataframe.
To drop levels in individual plots, you can create 2 plots and then place them side by side.
df2 <- df[df$sex==1,]
p1 <- ggplot(df2, aes(y=(reorder(id, id))))
p1 <- p1 + geom_point(aes(x=year))
p1
df3 <- df[df$sex==0,]
p2 <- ggplot(df3, aes(y=(reorder(id, id))))
p2 <- p2 + geom_point(aes(x=year))
If you notice, the id's without data are dropped. For example the following doesn't have id=2.
Now, you can use the gridExtra package which is meant for this purpose, to print out both the plots p1 and p2.
require(gridExtra)
grid.arrange(p1, p2, ncol=2)
facet_grid() includes all levels by design
Using facet_grid directly won't work, but this is by design. Facet_grip has the drop=TRUE by default. Notice that you are not seeing id's=5 or 6. If an id appears in any one panel, it is included in all the other panels to facilitate comparison.
p <- ggplot(df, aes(y=reorder(id, id)))
p <- p + geom_point(aes(x=year))
p <- p + facet_grid(sex ~.)
p