# Column-wise operations {#sec-column-wise}

```{r}
#| results: "asis"
#| echo: false
source("_common.R")
status("drafting")
```

## Introduction

<!--# TO DO: Write introduction. -->

### Prerequisites

In this chapter we'll continue using dplyr.
dplyr is a member of the core tidyverse.

```{r}
#| label: setup
#| message: false

library(tidyverse)
```

<!--# TO DO: Write chapter around across, etc. -->