I'm trying to calculate the difference b/w minimum and maximum date by group in R. The code to achieve this I found here. However, replicating the example does not lead to the expected result. This is the dataset example that was used:
HS_Hatch <- structure(list(ClutchID = c(1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L,
2L, 3L, 3L, 3L, 4L, 4L, 4L, 4L, 4L, 4L, 5L, 5L, 5L, 5L, 5L, 5L
), DateVisit = c("3/15/2012", "3/18/2012", "3/20/2012", "4/1/2012",
"4/3/2012", "3/18/2012", "3/20/2012", "3/22/2012", "4/3/2012",
"4/4/2012", "3/22/2012", "4/3/2012", "4/4/2012", "3/18/2012",
"3/20/2012", "3/22/2012", "4/2/2012", "4/3/2012", "4/4/2012",
"3/20/2012", "3/22/2012", "3/25/2012", "3/27/2012", "4/4/2012",
"4/5/2012"), Year = c(2012L, 2012L, 2012L, 2012L, 2012L, 2012L,
2012L, 2012L, 2012L, 2012L, 2012L, 2012L, 2012L, 2012L, 2012L,
2012L, 2012L, 2012L, 2012L, 2012L, 2012L, 2012L, 2012L, 2012L,
2012L), Survive = c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L)), class = c("tbl_df",
"tbl", "data.frame"), row.names = c(NA, -25L), .Names = c("ClutchID",
"DateVisit", "Year", "Survive"), spec = structure(list(cols = structure(list(
ClutchID = structure(list(), class = c("collector_integer",
"collector")), DateVisit = structure(list(), class = c("collector_character",
"collector")), Year = structure(list(), class = c("collector_integer",
"collector")), Survive = structure(list(), class = c("collector_integer",
"collector"))), .Names = c("ClutchID", "DateVisit", "Year",
"Survive")), default = structure(list(), class = c("collector_guess",
"collector"))), .Names = c("cols", "default"), class = "col_spec"))
This was the proposed solution using dplyr:
library(dplyr)
HS_Hatch <- HS_Hatch %>%
mutate(date_visit = as.Date(DateVisit, "%m/%d/%Y"))
exposure <- HS_Hatch %>%
group_by(ClutchID) %>%
summarize(first_visit = min(date_visit),
last_visit = max(date_visit),
exposure = last_visit - first_visit)
This is the expected result:
ClutchID first_visit last_visit exposure
<int> <date> <date> <dbl>
1 1 2012-03-15 2012-04-03 19
2 2 2012-03-18 2012-04-04 17
3 3 2012-03-22 2012-04-04 13
4 4 2012-03-18 2012-04-04 17
5 5 2012-03-20 2012-04-05 16
This is the actual result:
first_visit last_visit exposure
1 2012-03-15 2012-04-05 21 days
It seems that the grouping factor gets ignored. How do i have it calculate the date difference per ClutchID?
It works with just dplyr loaded.
Change summarize to dplyr::summarize to make it unambiguous. I would suggest not using plyr as you can do everything with dplyr and tidyverse.