README.Rmd

---
output: github_document
---

<!-- README.md is generated from README.Rmd. Please edit that file -->

```{r, echo = FALSE}
knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>",
  fig.path = "images/"
)
```

# nhdR

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The goal of nhdR is to provide R tools for interacting with the [National Hydrography Dataset](https://nhd.usgs.gov/).

## Installation

You can install nhdR from github with:

```{r gh-installation, eval = FALSE}
# install.packages("devtools")
devtools::install_github("jsta/nhdR")
```

## Usage
### Load package

```{r }
library(nhdR)
```

### NHD Plus

Unlike the standard NHD, the NHD-Plus exports are organized by vector processing unit (vpu). See below for a low resolution vpu map (also `nhdR::vpu_shp`). A hi-res version can be found [here](http://www.horizon-systems.com/NHDPlus/NHDPlusV2_data.php).

```{r echo=FALSE, message=FALSE, warning=FALSE}
library(ggplot2)
library(stringr)

dt <- nhdR::vpu_shp#[,"UnitID"]
dt <- dt[dt$UnitType == "VPU",]

centroid_xy <- sf::st_as_text(sf::st_geometry(sf::st_centroid(dt[,"UnitID"])))
extract_coords <- function(messy_centroid){
  res <- stringr::str_split(messy_centroid, "\\(", simplify = TRUE)[2]
  res <- stringr::str_split(res, "\\)", simplify = TRUE)[1]
  stringr::str_split(res, " ", simplify = TRUE)
}

coords <- data.frame(matrix(
            as.numeric(unlist(lapply(centroid_xy, extract_coords))),
            ncol = 2, byrow = TRUE), stringsAsFactors = FALSE)
names(coords) <- c("x", "y")
coords$x <- coords$x * -1
coords$UnitID <- dt[,"UnitID"]$UnitID

ggplot(dt) +
  geom_sf(aes(fill = UnitID), show.legend = FALSE) +
  xlim(126, 70) +
  ylim(23, 52) +
  geom_text(data = coords, aes(x = x, y = y, label = UnitID)) +
  theme_minimal() +
  theme(axis.title = element_blank()) +
  ggtitle("Vector Processing Units (VPU)")
```

```{r eval=FALSE}
# get a vpu export
nhd_plus_get(vpu = 4, "NHDSnapshot")
nhd_plus_get(vpu = 4, "NHDPlusAttributes")
nhd_plus_get(vpu = 4, "NHDPlusCatchment")
```

```{r }
# list layers
nhd_plus_list(vpu = 4, "NHDSnapshot")
nhd_plus_list(vpu = 4, "NHDPlusAttributes")
nhd_plus_list(vpu = 4, "NHDPlusCatchment")
```

```{r eval=FALSE}
# get layer info
nhd_plus_info(vpu = 4, "NHDSnapshot", "NHDWaterbody")
```

```{r echo=FALSE}
info <- capture.output(nhd_plus_info(vpu = 4, "NHDSnapshot", "NHDWaterbody"))
# gsub("/home/jose", "~", info)
info[2:length(info)]
```

```{r }
# load layer
dt <- nhd_plus_load(vpu = 4, "NHDSnapshot", "NHDWaterbody")
```

### NHD

```{r eval=FALSE}
nhd_get(state = c("DC", "HI"))
```

```{r }
nhd_list(state = "DC")
```

```{r }
nhd_info(state = "DC", dsn = "NHDWaterbody")
```

```{r }
head(nhd_load(state = "DC", dsn = "NHDWaterbody"))
```