Reshaping data in R

reshape.R

library(dplyr)
library(tidyr)

## make wide toy data
df <- data.frame(schid = c('A','B','C','D'),
                 year = 2013,
                 var_x = 1:4,
                 var_y = 5:8,
                 var_z = 9:12,
                 stringsAsFactors = FALSE) %>%
    tbl_df()

## gather (wide --> long)
df_long <- df %>%
    gather(var, value, -c(schid, year)) %>%
    mutate(var = gsub('var_', '', var)) %>%
    arrange(schid, var)

## spread (long --> wide)
df_wide <- df_long %>%
    mutate(var = gsub('(.*)', 'var_\\1', var)) %>%
    spread(var, value) %>%
    arrange(schid)

## print df
df
df_long
df_wide

## confirm that df_wide == df
identical(df, df_wide)

## -- NOTES --
## mutate() commands not strictly necessary; just for -/+ stub names
## tbl_df() not necessary; just makes printing nicer