在ggplot2中制作多个构面

Question

Hello I the following data set called States from the package carData in R. I am trying to plot the following data.

head(States)

   region      pop SATV SATM percent dollars pay
AL    ESC     4041  470  514       8   3.648  27
AK    PAC      550  438  476      42   7.887  43
AZ    MTN     3665  445  497      25   4.231  30
AR    WSC     2351  470  511       6   3.334  23
CA    PAC    29760  419  484      45   4.826  39
CO    MTN     3294  456  513      28   4.809  31

What I want to do is create a plot which shows four data from this chart. I want like a multiple facet chart.

Where my two variable on the vertical axes are SATV and SATM and my two variables on the horizontal axis are dollar and pay.

So for example there would be like four boxes and my top right would be the relation between pay and satv.

How can I do this using lattice or ggplot2.

Answer 1

I assumed at first glance that this was a matter of making a scatterplot matrix. @Punintended suggested GGally::ggpairs , and there might be something in GGally::ggduo that works too. But since you aren't looking for all combinations of variables, I realized that this is actually about reshaping the data: You have 2 independent variables, dollars and pay , and 2 dependents, SATV and SATM . You can reshape it so there's a column of test types and a column of test scores, and then reshape again to make a column of funding types and a column of funding amounts. I did this with two calls of tidyr::gather .

library(dplyr)
library(tidyr)
library(ggplot2)

data(States, package = "carData")

states_long <- States %>%
  gather(key = test_type, value = score, SATV, SATM) %>%
  gather(key = funding_type, value = funding_value, dollars, pay)

head(states_long)
#>   region   pop percent test_type score funding_type funding_value
#> 1    ESC  4041       8      SATV   470      dollars         3.648
#> 2    PAC   550      42      SATV   438      dollars         7.887
#> 3    MTN  3665      25      SATV   445      dollars         4.231
#> 4    WSC  2351       6      SATV   470      dollars         3.334
#> 5    PAC 29760      45      SATV   419      dollars         4.826
#> 6    MTN  3294      28      SATV   456      dollars         4.809

After that, facetting will work, because you now have some way to split the data apart, by funding type (dollars spent or pay) versus test type (verbal or math).

ggplot(states_long, aes(x = funding_value, y = score)) +
  geom_point() +
  facet_grid(test_type ~ funding_type, scales = "free")

Created on 2018-07-11 by the reprex package (v0.2.0).