# Select Data – First entry + set time period (1 year) R

## Issue

I have a dataset on a group of individuals that was collected starting at different times for each individual.

I need to subset the data from 1 year since their first entry, like so: `myData[myDate >= "first entry" & myDate += "1 year"]`

Example data:

``````df_date <- data.frame( Name = c("Jim","Jim","Jim","Jim","Jim","Jim","Jim","Jim","Jim","Jim","Jim","Jim","Jim","Jim",
"Sue","Sue","Sue","Sue","Sue","Sue","Sue","Sue","Sue","Sue","Sue","Sue","Sue","Sue"),
Dates = c("2010-1-1", "2010-2-2", "2010-3-5","2010-4-17","2010-5-20",
"2010-6-29","2010-7-6","2010-8-9","2010-9-16","2010-10-28","2010-11-16","2010-12-28","2011-1-16","2011-2-28",
"2010-4-1", "2010-5-2", "2010-6-5","2010-7-17","2010-8-20",
"2010-9-29","2010-10-6","2010-11-9","2012-12-16","2011-1-28","2011-2-28","2011-3-28","2011-2-28","2011-3-28"),
Event = c(1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1) )
``````

The desired output would be Jim would have data from `1/1/2010 - 12/28/2010` and Sue from `4/4/2010 - 3/28/2011` and so on. The actual dataset had > 20 samples, all starting at different times.

## Solution

Use a combination of `tidyverse` and `lubridate` functions:

``````library(tidyverse)
library(lubridate)

df_date %>%
mutate(Dates = as_datetime(Dates)) %>%
group_by(Name) %>%
arrange(Dates, .by_group = T) %>%
filter(Dates <= first(Dates) + duration(1, units = "year"))
``````

Answered By – Martin C. Arnold

Answer Checked By – Candace Johnson (AngularFixing Volunteer)