applyConversions {compareMCMCs}

Apply a set of parameter conversions to MCMC output

Description

Create transformed parameters from original parameters in MCMC output

Usage

applyConversions(samples, conversions)

Arguments

samples

One of: an MCMCresult object; a named list of MCMCresult objects (such as returned by compareMCMCs); a matrix of MCMC samples (such as the samples element of an MCMCresult object); or a named list of such matrices. In the first two cases, conversions will be done in place (as a "side effect" modifying the arguments) because MCMCresult objects are R6 objects and are thus passed by reference.

conversions

One of: a list of conversion specifications (see below); a named list of conversion specifications, with names matching those of a list provided for samples.

Details

A conversion specification is a named list. For each element:

• its name will be the name of a new column appended to a samples matrix.

• its value should be a character string that can be parsed as code to calculate elements of the new column. It can use existing column names in samples. Calculations will be done row-wise. Column names are often something like "beta[2]". To have this used as a name, enclose it in backticks, e.g. "`beta[2]`". For example, an entry could be ⁠log_beta2 = "log(`beta\[2\]`)"⁠. A list value of NULL will remove the named column.

The conversion specification list will be processed in order. This allows creating new columns and removing old ones in a sensible order.

If both conversions and samples are named lists, they will be matched: the conversions element (itself a list of conversion specifications) used on a samples element will have the same name. If there is no conversions element for a given samples element, that samples element will be included in the returned list without any conversions.

Value

An object of the same type as samples after application of conversions.