MigrationDetectR (version 0.1.1)

identify_migrations: identify_migrations

Description

identify_migrations

Usage

identify_migrations(
  segs,
  locs,
  min_res_length = 90,
  occurrence_locs = NULL,
  occurrence_times = NULL,
  verbose = TRUE
)

Value

A tibble containing the detected true relocations, if any. Contains the fields:

• from Character, the location from which the relocations started.

• to Character, the location from which the relocations started.

• movement_interval interval of the transitionary period, starting with the end of the prior residency and ending with the start of the new residency.

• movement_length The duration of the transitionary period in seconds.

• movement_midrange The midpoint of the transitionary period.

If occurrence_locs and occurrence_times were provided, find_best_split will be used to detect the optimum split time, and the following columns will be added:

• split_time, a POSIXct which indicates the time of the optimal split.

• split_correctness, a numeric which as a quality measure of splot_time reports the split's ratio of wrongly assigned days to the correctly assigned days.

Arguments

segs

A vector of interval, a vector of intervals which indicate residence segments, such as detected by detect_segments.

locs

A vector of Character, locations which correspond to segs.

min_res_length

(Optional) Numeric. A vector of days indicating the minimum number of days for segs to quality as viable origin or destination of a migration. Default is 90.

occurrence_locs

(Optional) Character. See occurrence_times

occurrence_times

(Optional) If provided along with the matching occurrence_times, will try to find the optimal point in time during which the migration occurred.

verbose

(Optional) logical. Output optional messages? Default is TRUE.

Author

Johannes Mast , based on the algorithm by Guanghua Chi

References

Chi, Guanghua, Fengyang Lin, Guangqing Chi, and Joshua Blumenstock. 2020. “A General Approach to Detecting Migration Events in Digital Trace Data.” Edited by Song Gao. PLOS ONE 15 (10): e0239408. https://doi.org/10.1371/journal.pone.0239408.

Examples

trace <- MigrationDetectR::example_trace
# Detect segments
segments <-
  detect_segments(
      locs = trace$location,
      times = trace$timestamp,
      param_min_days = 3,
      param_prop_days = 0.06,
      param_window_size_days = 7)
 nrow(segments) # check the number of detected segments

 migrations <-
 identify_migrations(
  segs = segments$segments,
  locs = segments$locs,
  min_res_length = 90,
  occurrence_locs = trace$location,
  occurrence_times = trace$timestamp
  )
  nrow(migrations) # check the number of identified migrations
  head(migrations) # check the detected migrations