Question

I’m using R to generate a plot from a table.

I used the command a <- read.table("table.txt") and that worked fine. When I type “a” it prints out my full table correctly.

I also entered library(ggplot2) so I could use ggplot.

Here was my first command:

ggplot(a, aes(x=V2, y=V5, group=V7)) + 
   geom_point(size=4, aes(col=V7)) + xlab("Rank") + 
   ylab("Inter-helix angle (Degree)") + 
   opts(legend.position="none") 

this command generated all the points, but when I added xlim(0,110) + ylim(0,110) to the end, it gave me a warning and said “Removed 101 Rows containing missing values” (my table is 101 rows long). The plot that was generated was completely empty. What happened?

Answer 1

I’m guessing perhaps your data falls out of the ranges you have specified in xlim and ylim e.g.:

 library(ggplot2)
 df <- data.frame(x=1:10,y=1:10)
 ggplot(a, aes(x=x, y=y)) + 
 geom_point(size=4) + xlab("Rank") + 
 ylab("Inter-helix angle (Degree)")

works fine, but:

 ggplot(df, aes(x=x, y=y)) + 
 geom_point(size=4) + xlab("Rank") + 
 ylab("Inter-helix angle (Degree)") + xlim(0,0.1) + ylim(0,0.1)

gives the same error as you get because no values fall between 0 and 0.1

Warning message:
Removed 10 rows containing missing values (geom_point).

Although without your data this is just the most likely answer. By the way in general folk tend to use coord_cartesian:

ggplot(df, aes(x=x, y=y)) + 
 geom_point(size=4) + xlab("Rank") + 
 ylab("Inter-helix angle (Degree)") + coord_cartesian(xlim=c(0,0.1)) + 
coord_cartesian(ylim=c(0,0.1))