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Update 04-spatial-operations.Rmd - Fig 4.10 refers to different code … #1161

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Nowosad merged 1 commit into from
Jun 17, 2025
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Update 04-spatial-operations.Rmd - Fig 4.10 refers to different code … #1161

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10 changes: 5 additions & 5 deletions 04-spatial-operations.Rmd
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Expand Up @@ -853,11 +853,7 @@ elev[clip]
# terra::extract(elev, ext(clip))
```

This amounts to retrieving the values of the first raster object (in this case `elev`) that fall within the extent of a second raster (here: `clip`), as illustrated in Figure \@ref(fig:raster-subset).

```{r raster-subset, echo = FALSE, fig.cap = "Original raster (left), raster mask (middle), and output of masking a raster (right).", fig.scap="Subsetting raster values."}
knitr::include_graphics("images/04_raster_subset.png")
```
This amounts to retrieving the values of the first raster object (in this case `elev`) that fall within the extent of a second raster (here: `clip`).

The example above returned the values of specific cells, but in many cases spatial outputs from subsetting operations on raster datasets are needed.
This can be done by setting the `drop` argument of the `[` operator to `FALSE`.
Expand All @@ -879,6 +875,10 @@ plot(x)
Another common use case of spatial subsetting is when a raster with `logical` (or `NA`) values is used to mask another raster with the same extent and resolution, as illustrated in Figure \@ref(fig:raster-subset).
In this case, the `[` and `mask()` functions can be used (results not shown).

```{r raster-subset, echo = FALSE, fig.cap = "Original raster (left), raster mask (middle), and output of masking a raster (right).", fig.scap="Subsetting raster values."}
knitr::include_graphics("images/04_raster_subset.png")
```

```{r 04-spatial-operations-38, eval=FALSE}
# create raster mask
rmask = elev
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