In jhnhng/trekR: Migration Classifier

knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>"
)

library(trekR)
library(lubridate)
library(dplyr)
library(tibble)

Setting Up the Data

Create Intervals

We created 10-day intervals for deer in the January and July. We first created a start column using the floor_Date() function to obtain the 10-day extents within the months. We included the 31st day (if a month had 31 days) in the third 10-day interval to prevent the creation of a 4th 10-day interval with only a single day in it.

Intervals for January

jan <- deer %>%
  # Creates a start column assigning the first day in the 10-day interval in which
  # the date falls under (e.g., 01-03-2021 would be in the first 10-day interval
  # so the `floor_date` assigned to it would be 01-01-2021)
  mutate(start = floor_date(date, "10 days")) %>%
  # For any months that has 31 days, the 31st day would normally be assigned its 
  # own interval. The code below takes the 31st day and joins it with the 
  # previous interval. 
  group_by(ID) %>% 
  mutate(start = if_else(day(start) == 31, start - days(10), start)) %>% 
  group_by(start, .add = TRUE) %>%
  filter(month == "1") %>% 
  group_split()

Let's remove some list elements from the jan interval so that we have different number of intervals between jan and july.

jan <- jan[-c(17,18)]

Intervals for July

july <- deer %>%
  # Creates a start column assigning the first day in the 10-day interval in which
  # the date falls under (e.g., 01-03-2021 would be in the first 10-day interval
  # so the `floor_date` assigned to it would be 01-01-2021)
  mutate(start = floor_date(date, "10 days")) %>%
  # For any months that has 31 days, the 31st day would normally be assigned its 
  # own interval. The code below takes the 31st day and joins it with the 
  # previous interval. 
  group_by(ID) %>% 
  mutate(start = if_else(day(start) == 31, start - days(10), start)) %>% 
  group_by(start, .add = TRUE) %>%
  filter(month == "7") %>% 
  group_split()

Assign names to the list elements

The names that are assigned to each list element is specific to that interval. In this case, we use the ID and start columns in the list element to assign a name. These names are important because they are later used to determine which elements are missing between the two list objects.

names(jan) <- sapply(jan, function(x) paste(x$ID[1],
                                            x$start[1], sep = '_'))

names(july) <- sapply(july, function(x) paste(x$ID[1],
                                              x$start[1],sep = '_'))

Matching Intervals

Using the match_intervals function we can match the number of intervals in july to those in jan. In this case, the first argument list1 is the reference list for the second argument list2.

july <- match_intervals(list1 = jan, list2 = july)

jhnhng/trekR documentation built on April 25, 2022, 12:43 p.m.