I'm quite new to R and need some help please.
There is a data frame for the growth of a certain plant with 2 columns. One shows the days (1, 2, 3, 4...) and one shows the weight of a plant.
I would like to have a code, that gives the day at which the mass reaches or exceeds 350g.
In other words, if value of weight-column reaches or exceeds 350, then give the value of the first column.