slides-turning-data-frames-into-sf-objects.qmd

---
title: Turning Data Frames into sf Objects
---

```{r}
#| echo: false
library(tidyverse)
library(sf)
```

```{r}
#| eval: false
#| echo: false

# https://www.portlandmaps.com/metadata/index.cfm?&action=DisplayLayer&LayerID=52777
library(janitor)

portland_corners <-
  read_sf("data/Corners_Improved.geojson") |>
    st_make_valid() |>
    st_centroid()

portland_corners |>
  clean_names() |>
  select(asset_id, ramp_style) |>
  st_coordinates() |>
  as_tibble() |>
  rename(longitude = X, latitude = Y) |>
  write_csv("data/portland-corners.csv")
```

### `st_as_sf()`

```{r}
#| eval: false
library(sf)

csv_file |>
  st_as_sf(
    coords = c("x_variable", "y_variable"),
    crs = 4326
  )
```

::: {.notes}
Talk about having to put variable names in quotes

Talk about crs: show how not adding CRS makes it not show up correctly on map
:::

---

```{r}
portland_corners_csv <-
  read_csv("data/portland-corners.csv")
```

. . .
```{r}
portland_corners_csv
```

---

```{r}
portland_corners_sf <-
  portland_corners_csv |>
    st_as_sf(
      coords = c("longitude", "latitude"),
      crs = 4326
    )
```


. . .

```{r}
portland_corners_sf
```

---

```{r}
portland_corners_sf |>
  mapview::mapview()
```



### Your Turn {.your-turn}

1. [Download this CSV](https://raw.githubusercontent.com/rfortherestofus/mapping-with-r-v2/refs/heads/main/data/portland-traffic-signals.csv) of traffic signal data for the city of Portland

1. Import the CSV and turn it into an `sf` object using `st_as_sf()`

1. Run `mapview::mapview()` to ensure you imported it correctly