r -ggplot :Discrete y axis entries in ggplot?

Question

I have a question about plotting in ggplot, or r in general.

If I have a data frame that looks something like this:

df <- data_frame(Patients = c(1:10),
                 test1 = sample(c(0,1), 10, replace = TRUE),
                 test2 = sample(c(0,1), 10, replace = TRUE),
                 test3 = sample(c(0,1), 10, replace = TRUE),
                 test4 = sample(c(0,1), 10, replace = TRUE))

Then the output looks like this.

# A tibble: 10 x 5
   Patients test1 test2 test3 test4
      <int> <dbl> <dbl> <dbl> <dbl>
 1        1     0     1     1     0
 2        2     1     0     1     1
 3        3     1     0     0     1
 4        4     1     1     0     1
 5        5     1     0     1     1
 6        6     1     0     0     1
 7        7     1     1     1     0
 8        8     1     0     0     1
 9        9     1     0     1     1
10       10     0     1     0     1

How can I make a graph where the patients are on the x-axis as discrete entries, and the y axis has four discrete entries, one for each test?

For example: enter image description here

I would also like to order the x axis by the number of matching tiles, like this.

enter image description here

Thanks very much for you time.

eipi10 eipi10 · Accepted Answer · 2017-06-29T21:20:41

We reshape the data into long format, calculate the number of tests by patient and use that to convert Patients to a factor with the desired ordering.

library(tidyverse)
library(forcats)
library(stringr)
theme_set(theme_minimal())

set.seed(2)
df <- data_frame(Patients = c(1:10),
                 test1 = sample(c(0,1), 10, replace = TRUE),
                 test2 = sample(c(0,1), 10, replace = TRUE),
                 test3 = sample(c(0,1), 10, replace = TRUE),
                 test4 = sample(c(0,1), 10, replace = TRUE))

ggplot(gather(df, Test, value, -Patients) %>%
         group_by(Patients) %>%
         mutate(Test = str_to_title(gsub("(.*)([0-9])", "\\1 \\2", Test)),
                numTests = sum(value)) %>%
         ungroup %>%
         arrange(numTests, Patients) %>%
         mutate(Patients = fct_inorder(factor(Patients))), 
       aes(Patients, Test, fill=factor(value))) +
  geom_tile(colour="grey60", lwd=0.8, show.legend=FALSE) +
  scale_fill_manual(values=c("white","black")) +
  labs(x="Patient", y="")

r -ggplot :Discrete y axis entries in ggplot?

1 Answers