select_between_polygons: Select tracks between two polygons.

In psyosphere: Analyse GPS Data

Description

Select tracks between a start and a finish polygon. Only the data between the polygons will remain. Data that is not between the start and finish polygon will be disregarded. If a track passes multiple times first the start and then the finish will be split up in rounds and new track id's will be created for each round.

Usage

select_between_polygons(
  tracks, poly1, poly2, t_id = "id", merge_id = TRUE
)

Arguments

tracks	psyo. Data frame with tracks.
poly1	data frame. A data frame with the columns lon (numeric) and lat (numeric). All coordinates will be selected that start after leaving this polygon and enter polygon_finish. The polygon should be closed, therefore the first and last coordinate must be the same. See also point.in.polygon.
poly2	data frame. A data frame with the columns lon (numeric) and lat (numeric). All coordinates will be selected that start after leaving polygon_start and enter this polygon. The polygon should be closed, therefore the first and last coordinate must be the same. See also point.in.polygon.
t_id	character or numeric. Column name in tracks that identifies the separate tracks.
merge_id	logical. If TRUE append the round to the current track id column t_id. If FALSE create a separate column with the round number.

Details

The following image shows a track before selection.

The following image shows a track after selection with 3 rounds.

Author(s)

Benjamin Ziepert. Please send feedback to: [e-mail].

Examples

## Not run: \dontrun{
# Create polygons
lon <- c(6.849975, 6.849627, 6.850001, 6.850350, 6.849975)
lat <- c(52.241745, 52.241100, 52.241004, 52.241649, 52.241745)
polygon_start <- data.frame(lon, lat)
remove(lon, lat)

lon <- c(6.851810, 6.851000, 6.851489, 6.852296, 6.851810)
lat <- c(52.241800, 52.240300, 52.240163, 52.241657, 52.241794)
polygon_finish <- data.frame(lon, lat)
remove(lon, lat)

# Get a track
data(psyo_rounds)

# Plot tracks
plot <- plot_tracks(psyo_rounds, zoom = 17, t_id = "")
plot

# Add start and finish polyon
plot <- plot_polygon(polygon_start, plot = plot)
plot_polygon(polygon_finish, plot = plot)

# Select data between polygon
psyo_rounds <- select_between_polygons(
  psyo_rounds, polygon_start, polygon_finish
)

# Plot the remaining data
plot <- plot_tracks(psyo_rounds, t_id = "")
plot <- plot_polygon(polygon_start, plot = plot)
plot_polygon(polygon_finish, plot = plot)
}
## End(Not run)

psyosphere documentation built on July 2, 2020, 12:08 a.m.