Plotting background data for groups

https://drsimonj.svbtle.com/plotting-background-data-for-groups-with-ggplot2

library(ggplot2)
ggplot(iris, aes(x = Sepal.Width)) +
  geom_histogram()

ggplot(iris, aes(x = Sepal.Width, fill = Species)) +
  geom_histogram()

ggplot(iris, aes(x = Sepal.Width)) +
  geom_histogram() +
  facet_wrap(~ Species)
#----
d <- iris        # Full data set
d_bg <- d[, -5]  # Background Data - full without the 5th column (Species)

ggplot(d, aes(x = Sepal.Width)) +
  geom_histogram(data = d_bg, fill = "grey") +
  geom_histogram() +
  facet_wrap(~ Species)

d <- iris        # Full data set
d_bg <- d[, -5]  # Background Data - full without the 5th column (Species)

ggplot(d, aes(x = Sepal.Width, fill = Species)) +
  geom_histogram(data = d_bg, fill = "grey", alpha = .5) +
  geom_histogram(colour = "black") +
  facet_wrap(~ Species) +
  guides(fill = FALSE) +  # to remove the legend
  theme_bw()  

ggplot(d, aes(x = Sepal.Width, y = Sepal.Length, colour = Species)) +
  geom_point(data = d_bg, colour = "grey", alpha = .2) +
  geom_point() + 
  facet_wrap(~ Species) +
  guides(colour = FALSE) +
  theme_bw()

Quick plot of all variables

https://drsimonj.svbtle.com/quick-plot-of-all-variables

library(purrr) #install.packages("purrr")
library(tidyr)
library(ggplot2)

mtcars %>%
  keep(is.numeric) %>% 
  gather() %>% 
  ggplot(aes(value)) +
  facet_wrap(~ key, scales = "free") +
  geom_histogram()
#---
d <- mtcars
d$vs <- factor(d$vs)
d$am <- factor(d$am)

library(tidyr)
d %>%
  keep(is.numeric) %>%                     # Keep only numeric columns
  gather() %>%                             # Convert to key-value pairs
  ggplot(aes(value)) +                     # Plot the values
  facet_wrap(~ key, scales = "free") +   # In separate panels
  geom_density()

Plot some variables against many others

https://drsimonj.svbtle.com/plot-some-variables-against-many-others

library(dplyr)
library(tidyr)



mtcars %>%
  gather(-mpg, -hp, key = "var", value = "value") %>%
  ggplot(aes(x = value, y = mpg, color = hp)) +
  geom_point() +
  facet_wrap(~ var, scales = "free") +
  theme_bw()

mtcars %>%
  gather(-mpg, -hp, -cyl, key = "var", value = "value") %>%
  ggplot(aes(x = value, y = mpg, color = hp, shape = factor(cyl))) +
  geom_point() +
  facet_wrap(~ var, scales = "free") +
  theme_bw()

mtcars %>%
  gather(-mpg, key = "var", value = "value") %>%
  ggplot(aes(x = value, y = mpg)) +
  geom_point() +
  stat_smooth() +
  facet_wrap(~ var, scales = "free") +
  theme_bw()