Any filter based on conditional criteria in r

Question

I would like to subset based on a specific criteria - any sort of conditional filter.

My data frame is a panel dataset of daily values for each day between 2004-2014.

Each day in the data frame is a separate observation. Each year has 366 days. I would like to subset the data such that only the leap years retain the 366th day in the panel data.

I need a script that will return a dataset without the 366th day but only for each year other than 2004, 2008, and 2012.

Can someone help me out with this?

Answer 1

Consider a data frame like this:

#Create DF
 year<-rep(c(2004:2014), each=366)
 day<-rep(c(1:366))
 df<-data.frame(day, year)

Set up data:

df  <- expand.grid(year=2004:2014,day=1:366)
nrow(df) ## 4026

Now exclude cases where (the year is not divisible by 4) AND (day equals 366) (identifying non-leap years would be trickier if you included 2000 and/or century-years in your dataset )

library(dplyr)
df2 <- df %>% filter(!(year %% 4 > 0 & day==366))