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cropping-and-subseting-your-presence-absence-matrix.Rmd
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cropping-and-subseting-your-presence-absence-matrix.Rmd
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---
title: "Cropping and subseting your presence absence matrix"
output: rmarkdown::html_vignette
vignette: >
%\VignetteIndexEntry{cropping-and-subseting-your-presence-absence-matrix}
%\VignetteEncoding{UTF-8}
%\VignetteEngine{knitr::rmarkdown}
editor_options:
chunk_output_type: console
---
```{r setup, include=FALSE}
knitr::opts_chunk$set(fig.height = 5, fig.width = 10, fig.align = 'center')
```
In this guide, we'll dive into the technique of subsetting or cropping a `PresenceAbsence` object.
To accomplish this task, we'll use the `lets.subsetPAM` function. Just let the function know which species you want to keep and provide the `PresenceAbsence` object as input.
```{r, message=FALSE, warning=FALSE}
# Package
library(letsR)
# Data
data("PAM")
names <- PAM$Species_name[1:20] # keep only the first 20 names
PAM_subset <- lets.subsetPAM(PAM, names)
par(mfrow = c(1, 2))
plot(PAM, main = "All species")
plot(PAM_subset, main = "Subset")
```
You might also find it useful to crop your `PresenceAbsence` object to a specific region using a shapefile. The `lets.pamcrop` function offers a straightforward method to achieve this. For instance, let's crop our Presence-Absence Matrix (PAM) to the borders of Brazil.
```{r}
data(wrld_simpl) # World map
data(PAM)
Brazil <- wrld_simpl[wrld_simpl$NAME == "Brazil", ] # Brazil (polygon)
PAM_crop <- lets.pamcrop(PAM, Brazil, remove.sp = TRUE)
par(mfrow = c(1, 2))
plot(PAM, main = "South America")
plot(PAM_crop, xlab = "Longitude", ylab = "Latitude",
main = "Phyllomedusa species richness (Brazil crop)")
plot(sf::st_geometry(wrld_simpl), add = TRUE)
```
**To cite letsR in publications use:**
*Bruno Vilela and Fabricio Villalobos (2015). letsR: a new R package for data handling and analysis in macroecology. Methods in Ecology and Evolution. DOI: 10.1111/2041-210X.12401*