Creating list with the same number of values - r

Question

I have a data set with a date, ID, and coordinates that I would like to split into seasonal months. For example for winter I have January to winter1, February to winter2, and March to winter3. I have done the same for the summer months.
I would like to filter out the IDs that have all of these months, so that when I split the data by ID and year, I would have identical list lengths.
I wasn't sure how to simulate uneven values for each ID in the sample code below, but in my actual data some IDs only have summer1 and not winter1, while it could be flipped around for summer2 and winter2`.
library(lubridate)
library(tidyverse)
date <- rep_len(seq(dmy("01-01-2010"), dmy("31-12-2013"), by = "days"),1000)
ID <- rep(seq(1, 5), 100)
df <- data.frame(date = date,
x = runif(length(date), min = 60000, max = 80000),
y = runif(length(date), min = 800000, max = 900000),
ID)
df$month <- month(df$date)
df$year <- year(df$date)
df1 <- df %>%
mutate(season_categ = case_when(month %in% 6 ~ 'summer1',
month %in% 7 ~ 'summer2',
month %in% 8 ~ 'summer3',
month %in% 1 ~ 'winter1',
month %in% 2 ~ 'winter2',
month %in% 3 ~ 'winter3')) %>%
group_by(year, ID )%>%
filter(any(month %in% 6:8) &
any(month %in% 1:3))
summer_list <- df1 %>%
filter(season_categ == "summer1") %>%
group_split(year, ID)
# Renames the names in the list to AnimalID and year
names(summer_list) <- sapply(summer_list,
function(x) paste(x$ID[1],
x$year[1], sep = '_'))
# Creates a list for each year and by ID
winter_list <- df1 %>%
filter(season_categ == "winter1") %>%
group_split(year, ID)
names(winter_list) <- sapply(winter_list,
function(x) paste(x$ID[1],
x$year[1], sep = '_'))

Answer 1

Not sure if that is what you want, but I understood that you would want to get rid of IDs that have less than the 6 months of Q1 and Q3 in any of the years, but you could modify the filter or grouping if that assumption was wrong.
Here is one approach:
library(lubridate)
library(dplyr)
set.seed(12345)
# random sampling of dates with this seed gives no July date for ID 2 in 2010
df <- tibble(
date = sample(seq(dmy("01-01-2010"), dmy("31-12-2013"), by = "days"),
1000, replace = TRUE),
x = runif(length(date), min = 60000, max = 80000),
y = runif(length(date), min = 800000, max = 900000),
ID = rep(1:5, 200),
month = month(date),
year =year(date)) %>%
arrange(ID, date)
df %>%
filter(month %in% c(1:3, 6:8)) %>%
group_by(ID, year) %>%
mutate(complete = length(unique(month)) == 6) %>%
group_by(ID) %>%
filter(all(complete)) %>%
group_by(ID, year) %>%
group_split()

Answer 2

To me it is not really clear as to what your are looking for. Before you split the data into a list sort the rows by columns
df1<-df1[order(ID,season_categ),]
### Determine which ID's have uneven numbers ###
df1 %>%
group_by(ID) %>%
summarize(month_seq = paste(season_categ , collapse = "_"),
number_of_months = n(season_categ))
#### Remove odd numbers###