Convert coordinate formats

Converts coordinate columns between decimal degrees, DMS (DDdeg MM'SS''}), and base-60 (\code{DDdeg MM') formats. Handles separate latitude and longitude columns as well as combined coordinate columns. Columns are converted in place; combined columns may optionally be split into separate latitude and longitude columns.

Usage

latlong_convert(
  data,
  column,
  convert = "decimal",
  type = "auto",
  drop_na = FALSE,
  split_combined = FALSE
)

Arguments

data

A data frame containing coordinate columns.

column

Column name or c() of column names to convert, supplied either unquoted (lat) or quoted ("lat").

convert

Character. Target coordinate format. One of "decimal" (default), "dms", or "base60".

type

Character. Coordinate type used for direction suffix assignment in DMS and base-60 output. One of "auto" (default), "lat", or "lon". When "auto", type is inferred from the column name (matching "lat" or "lon"/"lng"/"long") or from the value range if the name is uninformative.

drop_na

Logical. If TRUE, rows where any converted column contains NA are dropped after conversion. Default is FALSE.

split_combined

Logical. If TRUE, combined coordinate columns are split into two new columns named <column>_lat and <column>_lon rather than kept as a single combined column. Default is FALSE.

Value

The input data frame with converted coordinate columns. For non-combined columns, the original column is overwritten with the converted values. For combined columns, behavior depends on split_combined:

• If FALSE, the combined column is overwritten with converted values in the same delimited format.

• If TRUE, two new columns are appended — <column>_lat and <column>_lon — and the original column is retained.

When convert = "decimal", output columns are numeric. For "dms" and "base60", output columns are character.

Details

All input formats are first parsed to decimal degrees internally before conversion. The parser handles decimal, DMS, and base-60 formats, inferring sign from cardinal direction suffixes (S, W) or the sign of the degree value. Zero-width and BOM characters are stripped before parsing.

Combined columns are detected automatically by the presence of two or more numeric components in a single value. The separator used to split combined columns is assumed to be ","; use latlong_split if a custom separator is needed before converting.

Direction suffixes (N, S, E, W) are appended to DMS and base-60 output when type can be determined. If type = "auto" and the type cannot be inferred from the column name or value range, no suffix is added.

Use latlong_format to check input formats before conversion, and latlong_filter to remove out-of-range values beforehand.

See also

latlong_format for checking coordinate formats before conversion,

latlong_filter for removing out-of-range coordinates before conversion,

latlong_split for splitting combined columns with a custom separator prior to conversion,

latlong_combine for merging separate coordinate columns after conversion,

latlong_range for filtering to a bounding box after converting to decimal degrees,

latlong_region for filtering to named geographic regions after converting to decimal degrees.

Examples

df <- data.frame(
  id  = 1:4,
  lat = c(51.5, 48.8, -33.9, 40.7),
  lon = c(-0.1, 2.3, 151.2, -74.0)
)

# Convert decimal columns to DMS
latlong_convert(df, c(lat, lon), convert = "dms")
#> [latlong_convert] NA rows removed: 0
#>   id        lat         lon
#> 1  1  51°30′0″N     0°6′0″W
#> 2  2 48°47′60″N   2°17′60″E
#> 3  3 33°53′60″S 151°11′60″E
#> 4  4  40°42′0″N    74°0′0″W

# Convert to base-60
latlong_convert(df, c(lat, lon), convert = "base60")
#> [latlong_convert] NA rows removed: 0
#>   id     lat      lon
#> 1  1 51°30′N    0°6′W
#> 2  2 48°48′N   2°18′E
#> 3  3 33°54′S 151°12′E
#> 4  4 40°42′N   74°0′W

# Convert a single column, specifying coordinate type explicitly
latlong_convert(df, lat, convert = "dms", type = "lat")
#> [latlong_convert] NA rows removed: 0
#>   id        lat   lon
#> 1  1  51°30′0″N  -0.1
#> 2  2 48°47′60″N   2.3
#> 3  3 33°53′60″S 151.2
#> 4  4  40°42′0″N -74.0

# Convert a combined column and keep as single column
df_combined <- data.frame(
  coords = c("51.5,-0.1", "48.8,2.3", "-33.9,151.2")
)
latlong_convert(df_combined, coords, convert = "dms")
#> [latlong_convert] NA rows removed: 0
#>                    coords
#> 1      51°30′0″N, 0°6′0″W
#> 2   48°47′60″N, 2°17′60″E
#> 3 33°53′60″S, 151°11′60″E

# Convert a combined column and split into separate lat/lon columns
latlong_convert(df_combined, coords, convert = "decimal",
                split_combined = TRUE)
#> [latlong_convert] NA rows removed: 0
#>        coords coords_lat coords_lon
#> 1   51.5,-0.1       51.5       -0.1
#> 2    48.8,2.3       48.8        2.3
#> 3 -33.9,151.2      -33.9      151.2

# Drop rows that produce NA after conversion
df_na <- data.frame(
  lat = c(51.5, NA, 40.7),
  lon = c(-0.1, 2.3, -74.0)
)
latlong_convert(df_na, c(lat, lon), convert = "dms", drop_na = TRUE)
#> [latlong_convert] NA rows removed: 1
#>         lat      lon
#> 1 51°30′0″N  0°6′0″W
#> 3 40°42′0″N 74°0′0″W