How to add a plot name on the top left corner of the plot in R?

Question

I have two dataframes df1 and df2 as follows:

> df1
             dateTime value
1 2018-06-27 00:00:01     6
2 2018-06-27 00:00:02     2
3 2018-06-27 00:00:03     3
4 2018-06-27 00:00:04     1
> df2
             dateTime value
1 2018-06-27 00:00:01     3
2 2018-06-27 00:00:02     8
3 2018-06-27 00:00:03     4
4 2018-06-27 00:00:04     5

I want to plot these dataframes in just one diagram, split them to two different plots with same x axis and add their names to the top left corner of their plots. Note that dateTime is a POSIXct object. Here is the code:

library(grid)
library(dplyr)

plot1 <- df1 %>%
  select(dateTime, value) %>%
  ggplot() +
  geom_point(data = df1, aes(dateTime, value)) +
  geom_line(data = df1, aes(x = dateTime, y = value), color = 'green') +
  geom_text(aes(x = df1$dateTime[1], y = df1$value[1], label = "X Data"), color = "red", size = 7) +
  theme(axis.text=element_text(size = 14), axis.title=element_text(size = 14),
        axis.title.x=element_blank(),
        axis.text.x=element_blank(),
        axis.ticks.x=element_blank())

plot2 <- df2 %>%
  select(dateTime, value) %>%
  ggplot() +
  geom_point(data = df2, aes(dateTime, value)) + 
  geom_line(data = df2, aes(x = dateTime, y = value), color = 'red') +
  xlab("dateTime") +
  geom_text(aes(x = df2$dateTime[1], y = df2$value[1]+5, label = "Y Data"), color = "green", size = 7) +
  theme(axis.text=element_text(size = 14), axis.title=element_text(size = 14))

grid.newpage()
grid.draw(rbind(ggplotGrob(plot1), ggplotGrob(plot2), size = "last"))

And the result is:

As you can see, X Data and Y Data are in the top left corner, but I really do not like to manually change the coordinates in geom_text to get the exact position which I want. Is there a better way to do that without changing the coordinates manually?

Row bind 2 dataframes with ID column, then read about [facets](https://ggplot2.tidyverse.org/reference/facet_grid.html). — zx8754, Jun 12 '19 at 08:29
`cowplot::plot_grid(..., labels = )`. Dupe-oid: [Side-by-side plots with ggplot2](https://stackoverflow.com/questions/1249548/side-by-side-plots-with-ggplot2) — Henrik, Jun 12 '19 at 08:35

Otto Kässi · Answer 1 · 2019-06-12T09:06:01.073

1

I have used ?annotate to accomplish this. Here's a simple example:

library(ggplot2)
library(scales)
library(grid)

y <- c(6,2,3,1)
x <-  as.POSIXct(c('00:00:01', '00:00:02', '00:00:03', '00:00:04'), format = '%H:%M:%S')
df1 <- data.frame(x, y)

y2 <- c(3,8,4,2)
x2 <-  as.POSIXct(c('00:00:01', '00:00:02', '00:00:03', '00:00:04'), format = '%H:%M:%S')
df2 <- data.frame(cbind(x2, y2))

plot1 <- ggplot() + geom_point(data = df1, aes(x, y)) + 
scale_x_time(labels=time_format('%H:%M:%S', tz=Sys.timezone())) + 
annotate('text', label='first graph', x=-Inf, y=Inf, hjust=0, vjust=1)

plot2 <- ggplot() + geom_point(data = df2, aes(x2, y2)) + 
scale_x_time(labels=time_format('%H:%M:%S',  tz=Sys.timezone())) + 
annotate('text', label='second graph', x=-Inf, y=Inf, hjust=0, vjust=1)

grid.newpage()
grid.draw(rbind(ggplotGrob(plot1), ggplotGrob(plot2), size = "last"))

edited Jun 12 '19 at 09:06

answered Jun 12 '19 at 08:42

Otto Kässi

2,943
1
10
27

It doesn't work, because as I said the `x` axis (`dateTime`) is a `POSIXct` object. – Patris Jun 12 '19 at 08:45
Sorry, I have edited my reply to include scale_x_time(). – Otto Kässi Jun 12 '19 at 09:06
This is good, but for some reasons, I prefer to use `scale_x_datetime` instead of `scale_x_time`. In this case, I cannot use `annotate`. – Patris Jun 13 '19 at 09:56

How to add a plot name on the top left corner of the plot in R?

1 Answers1