tidybayes: combine_chains – R documentation

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combine_chains

Combine the chain and iteration columns of tidy data frames of draws

Description

Combines the chain and iteration columns of a tidy data frame of draws from a Bayesian model fit into a new column that can uniquely identify each draw. Generally speaking not needed for pure tidybayes code, as tidybayes functions now automatically include a .draw column, but can be useful when interacting with packages that do not provide such a column.

Usage

combine_chains(data, chain = .chain, iteration = .iteration, into = ".draw")

Arguments

`data`	Tidy data frame of draws with columns representing the chain and iteration of each draw.
`chain`	Bare name of column in `data` indicating the chain of each row. The default (`.chain`) is the same as used by other functions in `tidybayes`.
`iteration`	Bare name of column in `data` indicating the iteration of each row. The default (`.iteration`) is the same as used by other functions in `tidybayes`.
`into`	Name (as a character vector) of the column to combine chains into. The default, `NULL`, replaces the `chain` column with `NA`s and writes the combined chain iteration numbers into `iteration`. If provided, `chain` and `iteration` will not be modified, and the combined iteration number will be written into a new column named `into`.

Value

A data frame of tidy draws with a combined iteration column

Author(s)

Matthew Kay

Examples

library(magrittr)
library(coda)

data(line, package = "coda")

# The `line` posterior has two chains with 200 iterations each:
line %>%
  tidy_draws() %>%
  summary()

# combine_chains combines the chain and iteration column into the .draw column.
line %>%
  tidy_draws() %>%
  combine_chains() %>%
  summary()

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