`subsetHz()`

is a function used for extracting horizons from a SoilProfileCollection based on logical criteria.

```
# S4 method for class 'SoilProfileCollection'
subsetHz(x, ..., drop = TRUE)
```

## Arguments

- x
a SoilProfileCollection

- ...
Comma-separated set of R expressions that evaluate as `TRUE`

or `FALSE`

in context of horizon data frame. Length for individual expressions matches number of horizons, in `x`

.

- drop
Default: `TRUE`

. When `drop=FALSE`

placeholder horizons (profile ID with all other values `NA`

) are created where the specified filter results in removal of all horizons.

## Value

a SoilProfileCollection with a subset of horizons, possibly with some sites removed

## Details

To minimize likelihood of issues with non-standard evaluation context, especially when using `subsetHz()`

inside another function, all expressions used in `...`

should be in terms of variables that are in the horizon data frame.

## Examples

```
data(sp3)
depths(sp3) <- id ~ top + bottom
# show just horizons with 10YR hues
plot(subsetHz(sp3, hue == '10YR'))
```