r - how can I calculate mean of every 6 rows in a data frame based on the condition of other column?

Question

I have a dataframe in R, contain 3000 rows and 2 columns (temp, flag), I am trying to calculate "meantemp" as the third column for every 6 rows if the corresponding values in flag column are not NA, SO if flage values are equal to NA I want to show in the meantemp column NA value. sorry for this question.

question from:https://stackoverflow.com/questions/65661714/how-can-i-calculate-mean-of-every-6-rows-in-a-data-frame-based-on-the-condition

Answer 1

You can try :

library(dplyr)

df %>%
  group_by(group = ceiling(row_number()/6)) %>%
  mutate(meantemp = if(all(is.na(flag))) mean(temp, na.rm = TRUE) else NA) %>%
  ungroup() %>%
  select(-group) -> df