dos cadenas en una cadena r

> toString(ddf$year)
[1] "1983, 1983, 1983, 1983"
> 
> toString(ddf$period)
[1] "M01, M02, M03, M04"
> 
> paste(toString(ddf$year), toString(ddf$period))
[1] "1983, 1983, 1983, 1983 M01, M02, M03, M04"
Trustworthy Whale