Lapply to Add Columns to Each Dataframe in a List [duplicate]

Answer 1

Use Map. It is short for mapply(..., SIMPLIFY = FALSE) as suggested by Ari.

df1 <- data.frame(x = runif(3), y = runif(3))
df2 <- data.frame(x = runif(3), y = runif(3))
dfs <- list(df1, df2)
years <- list(2013, 2014)

Map(cbind, dfs, year = years)
# [[1]]
#           x         y year
# 1 0.8843945 0.6285246 2013
# 2 0.8400041 0.1369520 2013
# 3 0.4398870 0.4660476 2013
# 
# [[2]]
#           x         y year
# 1 0.4153315 0.5831114 2014
# 2 0.9685105 0.2398060 2014
# 3 0.9507591 0.7585670 2014