• Introduction
• Inside() andMultiverse analysis in R scripts
• Multiverse in RMarkdown
  • Multiverse code block
• Notes on using multiversecode blocks
  • In RStudio using RMarkdown
  • Knitting to HTML usingknitr
  • Knitting to HTML usingknitr
• Debugging Keyboard Shortcuts
  • On OS XSystems

library(knitr)library(dplyr)library(tidyr)library(purrr)library(multiverse)

Introduction

In this document we will describe the usage of the multiverse codeblock. The multiverse code block is an alternative to the R code blockwhich will parse any code run in it directly in the multiverse, andreduces the need for auxiliary functions such as (inside). In addition,the default analysis in the multiverse will be executed in theenvironment in which the multiverse has been declared, which wouldusually be the global environment. In that case the results of thedefault analysis can be inspected directly in an R code block, similarto what an user would do if they were running a single universeanalysis.

We demonstrate how the two methods are equivalent, and result in thesame multiverse.

In this example, we will use the data which compares differentmodalities for physical visualizations. See(frequentist-multiverse-analysis) for more details.

data("userlogs")

As with any multiverse analysis, we first need to define themultiverse object. This step is the same for both methods. We willdefine two separate objects for illustrating the two different ways ofadding code to the multiverse for analysis. In the multiverse analysisin this vignette, we will perform a log transformation on the durationvariable of the dataset using both theinside function aswell as themultiverse code block

M_inside=multiverse()M_block=multiverse()

Inside() and Multiverse analysis in R scripts

The idea of the inside function is to allow us to write code to beexecuted within the multiverse and not directly in R, thus allowing usto make use of a flexible syntax for declaring the different possibleanalysis combinations within the multiverse. The inside function takestwo arguments:

1. the name of the multiverse object
2. the expression (code) to be passed into the multiverse enclosedwithin a pair of curly braces,{

The expression passed into the multiverse is not executed directly,allowing us to parse and expand the expression provided by the user hasdeclared using ourbranch andparameters, intotheir corresponding analysis combinations.

inside(M_inside, {    data_transform<-branch(data_transform,"log-transformed"~ log,"untransformed"~ identity      )    duration<-do.call(data_transform,list(userlogs$duration))})

Multiverse in RMarkdown

Although the inside function is the only way to add code to themultiverse in an RScript, RMarkdown notebooks allow us the opportunityto use different language engines (not just limited to R). Thisflexibility also provides an opportunity to write multiverse codedirectly into a code block, instead of using auxillary functions.

The language associated with a code block is provided by the firstargument:```{r} Here the first argument isrhence the code in the associated block will be executed in R. To converta code block to execute in multiverse, change the first argument tomultiverse. Thus the code block would be:```{multiverse}

To execute a code block in multiverse, the user needs to provide twoadditional arguments:label andinside.

The label is a unique identifier for the code block, and each codeblock in the same document must have a different label. However, thelabel argument does not need to be explicitly specified (as is the casewith an R code block). Therefore,```{multiverse, label=default-m-1 ...},```{multiverse, default-m-1 ...} and```{multiverse default-m-1 ...} are all equivalent.

The inside argument takes in only multiverse objects, and is used toindicate the multiverse object which will the code inside the code blockwill be associated with. Thus declaring a multiverse code block wouldbe:```{multiverse, default-m-1, inside = M}

We provide the ability to declare multiverse code block as anAddIn in RStudio. Users can click onAddIns toolbarmenu in RStudio (see the image below). This would create a multiversecode block at the location of the cursor in the document.

Alternately, users can insert a multiverse We also allow users tocreate a keyboard shortcut to declare a multiverse code block inside aRMarkdown document. This can be done through the following steps:

• Tools > AddIns > Browse AddIns… > Keyboard Shortcuts
• Next, in the filter input field, typemultiverse. You willsee one result with “Insert multiverse code chunk” as the name.
• Click on the Shortcut field and press Cmd+Option+M (on Mac OS) orCtrl+Shift+Alt+M (on Windows).
• Click “Apply” and exit the dialog box

If you are experiencing issues creating a keyboard shortcut for codeblocks, or if you are experiencing a situation where the shortcut needsto be re-created everytime you open a new RStudio session, please referto theDebugging Keyboard Shortcuts section at the end ofthis document.

```{multiverse default-m-1, inside = M_block}data_transform <- branch(data_transform,    "log-transformed" ~ log,    "untransformed" ~ identity  )duration <- do.call(data_transform, list(userlogs$duration))```

expand(M_inside)

## # A tibble: 2 × 6##   .universe data_transform  .parameter_assignment .code        .results .errors##       <int> <chr>           <list>                <list>       <list>   <list> ## 1         1 log-transformed <named list [1]>      <named list> <env>    <lgl>  ## 2         2 untransformed   <named list [1]>      <named list> <env>    <lgl>

expand(M_block)

## # A tibble: 2 × 6##   .universe data_transform  .parameter_assignment .code        .results .errors##       <int> <chr>           <list>                <list>       <list>   <list> ## 1         1 log-transformed <named list [1]>      <named list> <env>    <lgl>  ## 2         2 untransformed   <named list [1]>      <named list> <env>    <lgl>

## [[1]]## [[1]]$`1`## {##     data_transform <- log##     duration <- do.call(data_transform, list(userlogs$duration))## }## ## ## [[2]]## [[2]]$`1`## {##     data_transform <- identity##     duration <- do.call(data_transform, list(userlogs$duration))## }

## [[1]]## [[1]]$`default-m-1`## {##     data_transform <- log##     duration <- do.call(data_transform, list(userlogs$duration))## }## ## ## [[2]]## [[2]]$`default-m-1`## {##     data_transform <- identity##     duration <- do.call(data_transform, list(userlogs$duration))## }

Notes on using multiverse code blocks

Debugging Keyboard Shortcuts