traipse (version 0.3.0)

track_query: Query track data for arbitrary locations

Description

Latent positions may be queried using arbitrary date-time values. The only method (for now) is 'linear', but default should be 'geodesic'. In time we include more methods to match the GeoPandas implementation.

Usage

track_query(x, y, date = NULL, query, type = "linear")

Value

data frame of 'x,y,date' of inferred positions

Arguments

x

longitude

y

latitude

date

date-time in POSIXct (or can be ignore, for relative index-time)

query

required argument, date-time values to return inferred x, y positions for

type

linear, geodesic, rhumb, forward, backward, nearest (also need open/closed intervals)

Details

If date is not included, time itself is treated as the obvious index on n-locations so simple relative time, and query is expected to match this.

We use group_modify to keep the id groups: trips0 %>% group_by(id) %>% group_modify(~track_query(.x$x, .x$y, query = c(4.5, 6.7)))

Examples

track_query(trips0$x[1:10], trips0$y[1:10], query = c(4.5, 5.5, 6.5))
track_query(trips0$x[1:10], trips0$y[1:10], trips0$date[1:10], query = trips0$date[1:10] + 10)
s <- seq(min(trips0$date), max(trips0$date), by = "1 hour")