Expand ranges defined by “from” and “to” columns

Question

I have a data frame containing \"name\" of U.S. Presidents, the years when they start and end in office, (\"from\" and \"to\" columns

Answer 1

Another solution using dplyr and tidyr:

library(magrittr) # for pipes
df <- data.frame(tata = c('toto1', 'toto2'), from = c(2000, 2004), to = c(2001, 2009))

#    tata from   to
# 1 toto1 2000 2001
# 2 toto2 2004 2009

df %>% 
  dplyr::as.tbl() %>%
  dplyr::rowwise() %>%
  dplyr::mutate(combined = list(seq(from, to))) %>%
  dplyr::select(-from, -to) %>%
  tidyr::unnest(combined)

#   tata  combined
#       
# 1 toto1     2000
# 2 toto1     2001
# 3 toto2     2004
# 4 toto2     2005
# 5 toto2     2006
# 6 toto2     2007
# 7 toto2     2008
# 8 toto2     2009