R - how to add spaces to last row elements in dataframe after line-CodePudding

Imagine a data frame...

df <- rbind("title", "------------------", "quite long content", "quite long content", "------------------", "short cont", "short cont")
df <- as.data.frame(df)
df

...which prints:

> df
                  V1
1              title
2 ------------------
3 quite long content
4 quite long content
5 ------------------
6         short cont
7         short cont

I would like to add spaces to all elements below the last line (they can vary in number) so they align with elements in the other lines, such that:

> df
                  V1
1              title
2 ------------------
3 quite long content
4 quite long content
5 ------------------
6       short cont
7       short cont

Could someone help me with a way to achieve this? Many thanks in advance.

CodePudding user response：

after_last_line <- !rev(cumany(grepl("^- $", rev(df$V1))))
after_last_line
# [1] FALSE FALSE FALSE FALSE FALSE  TRUE  TRUE
df$V1[after_last_line] <- paste0(df$V1[after_last_line], "  ")
df
#                   V1
# 1              title
# 2 ------------------
# 3 quite long content
# 4 quite long content
# 5 ------------------
# 6       short cont  
# 7       short cont