# Stand equality

## Mutate individual tree records

Calculate a new column from values recorded from an individual tree.

* 5 cm diameter classes
* diameter increment

```R
df |>
  mutate(newColumn = function(Value)
```

## Summarise functions

Calculate a single value for a group using `group_by() |> summarise()`

* q value
* Gini coefficient
* Shannon Diversity Index
* SDI
* transition period (C&A used cores)
* annual recruitment
* TH (filter just the height data)

```R
df |>
  group_by(Plot, Year) |>
  summarise(
    measure = function(Value)
  )
```

## Mutate aggregate values

Calculate a new column from group-level aggregate values

* form class
* form height

```R
df |>
  mutate(newColumn = function(Value)
```