R: Join two tables based on a geo distance of longitudes and...

geo_join {fuzzyjoin} | R Documentation

## Join two tables based on a geo distance of longitudes and latitudes

### Description

This allows joining based on combinations of longitudes and latitudes. If you are using a distance metric that is *not* based on latitude and longitude, use `distance_join` instead. Distances are calculated based on the `distHaversine`, `distGeo`, `distCosine`, etc methods in the geosphere package.

### Usage

    geo_join(x, y, by = NULL, max_dist, method = c("haversine", "geo", "cosine",
      "meeus", "vincentysphere", "vincentyellipsoid"), unit = c("miles", "km"),
      mode = "inner", distance_col = NULL, ...)

    geo_inner_join(x, y, by = NULL, method = "haversine", max_dist = 1,
      distance_col = NULL, ...)

    geo_left_join(x, y, by = NULL, method = "haversine", max_dist = 1,
      distance_col = NULL, ...)

    geo_right_join(x, y, by = NULL, method = "haversine", max_dist = 1,
      distance_col = NULL, ...)

    geo_full_join(x, y, by = NULL, method = "haversine", max_dist = 1,
      distance_col = NULL, ...)

    geo_semi_join(x, y, by = NULL, method = "haversine", max_dist = 1,
      distance_col = NULL, ...)

    geo_anti_join(x, y, by = NULL, method = "haversine", max_dist = 1,
      distance_col = NULL, ...)

### Arguments

`x` | A tbl
`y` | A tbl
`by` | Columns by which to join the two tables
`max_dist` | Maximum distance to use for joining
`method` | Method to use for computing distance: one of "haversine" (default), "geo", "cosine", "meeus", "vincentysphere", "vincentyellipsoid"
`unit` | Unit of distance for threshold (default "miles")
`mode` | One of "inner", "left", "right", "full" "semi", or "anti"
`distance_col` | If given, will add a column with this name containing the geographical distance between the two
`...` | Extra arguments passed on to the distance method

### Details

"Haversine" was chosen as default since in some tests it is approximately the fastest method. Note that by far the slowest method is vincentyellipsoid, and on fuzzy joins should only be used when there are very few pairs and accuracy is imperative.

If you need to use a custom geo method, you may want to write it directly with the `multi_by` and `multi_match_fun` arguments to `fuzzy_join`.

### Examples

    library(dplyr)
    data("state")

    # find pairs of US states whose centers are within
    # 200 miles of each other
    states <- data_frame(state = state.name,
                         longitude = state.center$x,
                         latitude = state.center$y)

    s1 <- rename(states, state1 = state)
    s2 <- rename(states, state2 = state)

    pairs <- s1 %>%
     geo_inner_join(s2, max_dist = 200) %>%
     filter(state1 != state2)

    pairs

    # plot them
    library(ggplot2)
    ggplot(pairs, aes(x = longitude.x, y = latitude.x,
                      xend = longitude.y, yend = latitude.y)) +
      geom_segment(color = "red") +
      borders("state") +
      theme_void()

    # also get distances
    s1 %>%
      geo_inner_join(s2, max_dist = 200, distance_col = "distance")

[Package fuzzyjoin version 0.1.4 Index]