tidybayes: gather_pairs – R documentation

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gather_pairs

Gather pairwise combinations of values from key/value columns in a long-format data frame

Description

Fast method for producing combinations of values in a value column for different levels of a key column, assuming long-format (tidy) data with an equal number of values per key. Among other things, this is useful for producing scatter-plot matrices.

Usage

gather_pairs(
  data,
  key,
  value,
  row = ".row",
  col = ".col",
  x = ".x",
  y = ".y",
  triangle = c("lower only", "upper only", "lower", "upper", "both only", "both")
)

Arguments

`data`	Tidy data frame.
`key`	Bare name of column in `data` containing the key .
`value`	Bare name of column in `data` containing the value.
`row`	Character vector giving the name of the output column identifying rows in the matrix of pairs (takes values of `key`).
`col`	Character vector giving the name of the output column identifying columns in the matrix of pairs (takes values of `key`).
`x`	Character vector giving the name of the output column with x values in the matrix of pairs (takes values of `value`).
`y`	Character vector giving the name of the output column with y values in the matrix of pairs (takes values of `value`).
`triangle`	Should the upper or lower triangle of the matrix of all possible combinations be returned? The default, `"lower only"`, returns the lower triangle without the diagonal; `"lower"` returns the lower triangle with the diagonal (`"upper"` and `"upper only"` operate analogously), `"both"` returns the full set of possible combinations, and `"both only"` returns all combinations except the diagonal. This method is particularly useful for constructing scatterplot matrices. See examples below.

Value

A tidy data frame of combinations of values in key and value, with columns row and col (default names ".row" and ".col") containing values from key, and columns y and x (default names ".y" and ".x") containing values from value.

Author(s)

Matthew Kay

Examples

library(ggplot2)
library(dplyr)

t_a = rnorm(100)
t_b = rnorm(100, t_a * 2)
t_c = rnorm(100)

df = rbind(
  data.frame(g = "a", t = t_a),
  data.frame(g = "b", t = t_b),
  data.frame(g = "c", t = t_c)
)

df %>%
  gather_pairs(g, t, row = "g_row", col = "g_col", x = "t_x", y = "t_y") %>%
  ggplot(aes(t_x, t_y)) +
  geom_point() +
  facet_grid(vars(g_row), vars(g_col))

df %>%
  gather_pairs(g, t, triangle = "upper") %>%
  ggplot(aes(.x, .y)) +
  geom_point() +
  facet_grid(vars(.row), vars(.col))

df %>%
  gather_pairs(g, t, triangle = "both") %>%
  ggplot(aes(.x, .y)) +
  geom_point() +
  facet_grid(vars(.row), vars(.col))

data(line, package = "coda")

line %>%
  tidy_draws() %>%
  gather_variables() %>%
  gather_pairs(.variable, .value) %>%
  ggplot(aes(.x, .y)) +
  geom_point(alpha = .25) +
  facet_grid(vars(.row), vars(.col))

line %>%
  tidy_draws() %>%
  gather_variables() %>%
  gather_pairs(.variable, .value) %>%
  ggplot(aes(.x, .y, color = factor(.chain))) +
  geom_density_2d(alpha = .5) +
  facet_grid(vars(.row), vars(.col))

tidybayes

Tidy Data and 'Geoms' for Bayesian Models

v2.3.1

GPL (>= 3)

Authors

Matthew Kay [aut, cre], Timothy Mastny [ctb]

Initial release

2020-10-30