Subsequent ID in list of dfs

Question

I have a list of dfs like:

Name <- c("Jon", "Bill", "Maria", "Ben", "Tina")
Age <- c(23, 41, 32, 58, 26)

df1 <- data.frame(Name, Age)

Name <- c("Jon", "Bill", "Maria", "Ben", "Tina")
Age <- c(23, 41, 32, 58, 26)
df2 <- data.frame(Name, Age)

list <- list(df1, df2)

I want to create a subsequent ID through all DFs. My desired Output should look like:

Name <- c("Jon", "Bill", "Maria", "Ben", "Tina")
Age <- c(23, 41, 32, 58, 26)
ID <- c(1:5)

df1 <- data.frame(Name, Age, ID)

Name <- c("Jon", "Bill", "Maria", "Ben", "Tina")
Age <- c(23, 41, 32, 58, 26)
ID <- c(5:9)
df2 <- data.frame(Name, Age, ID)
list <- list(df1, df2)

Answer 1

(I named it list1 instead of list, not wanting to confuse variables/functions :-)

I'm assuming df2 should start at nrow(df1) + 1, not at nrow(df1).

lens <- sapply(list1, nrow)
list1 <- Map(function(X, fm, len) transform(X, ID = fm + seq_len(len)),
             list1, c(0, lens[-length(lens)]), lens)
list1
# [[1]]
#    Name Age ID
# 1   Jon  23  1
# 2  Bill  41  2
# 3 Maria  32  3
# 4   Ben  58  4
# 5  Tina  26  5
# [[2]]
#    Name Age ID
# 1   Jon  23  6
# 2  Bill  41  7
# 3 Maria  32  8
# 4   Ben  58  9
# 5  Tina  26 10