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Compute summary statistics for each track

Source: R/track_summary_stats.R
track_summary_stats.Rd

This function provides a set of summary statistics for each track. It is unusual in returning a tibble of multiple variables rather than a single vector. The summary statistics include the duration of the track, the cumulative distance along the track, the maximum and minimum latitude and longitude of the track, and, if a central place location is provided, the maximum distance from that location, and the latitude and longitude at the most distant point from that location.

Usage

track_summary_stats(x, centre_col = NULL, units_duration = as_units(1, "days"))

Arguments

x

A move2 object

centre_col

The name of an sf point column (usually added with sf_point_col()) in the metadata table. If left as NULL, the first location of each track (i.e. the starting point) is used as the centre.

units_duration

The units to use for the duration. Default is "days".

Value

A tibble of summary statistics, with one row per track. The columns are:

  • <track id column>: The track ID from x

  • tot_duration: The total duration of the track in the specified units

  • tot_distance: The total distance travelled in the track

  • max_latitude: The maximum latitude of the track

  • min_latitude: The minimum latitude of the track

  • max_longitude: The maximum longitude of the track

  • min_longitude: The minimum longitude of the track

  • max_dist_centre: The maximum distance from the central place location in column centre_col (or the starting point)

  • lat_at_max_dist_centre: The latitude at the point of maximum distance from the central place location (or the starting point)

  • lon_at_max_dist_centre: The longitude at the point of maximum distance from the central place location (or the starting point)

Details

Note that the central place location is often not part of the track. This means that under certain circumstances (e.g. very large buffers used in trip splitting), the total distance travelled along the track may be shorter than the maximum distance from the central location. In this case, you could consider either using a smaller buffer for trip splitting, or manually adding an at-colony point at the start and end of the track.

The units for distance, latitude, and longitude are taken from the projection. The units for duration are specified by the units_duration argument.

Examples

track_summary_stats(example_tt)
#> # A tibble: 3 × 10
#>   track_id tot_duration tot_distance max_latitude min_latitude max_longitude
#>   <chr>             [d]          [m]        <dbl>        <dbl>         <dbl>
#> 1 a              0.0556     1174866.        3.53        -0.577         5.54 
#> 2 b              0.0556      870933.       -0.357       -1.94         -0.270
#> 3 c              0.0556      813408.        3.05         0.433        -0.784
#> # ℹ 4 more variables: min_longitude <dbl>, max_dist_centre [m],
#> #   lat_at_max_dist_centre <dbl>, lon_at_max_dist_centre <dbl>