r - Expand Row with Multiple Observations into Individual Rows

Question

Just wondering if there is a way to expand rows which have multiple observations, into rows of unique observations using R? I have data in an excel spreadsheet with the variable headings: Lease, Line, Bay, Date, Predators, Food.Index, DD, MM, YY.

On some dates, there have been multiple predators (from 1 to 4) recorded in the same row. Other days just have 0. On a day where there has been 4 predators recorded, I would like to somehow transform the data to show four unique observations (instead of one row with 4 recorded under "Predators").

I have 1669 rows of data and multiple rows need to be expanded

Example of Data set

Many thanks for your help in advance.

enter image description here

Answer 1

Assuming you have your data in a data.frame, df, one possible solution would be

df.expanded <- df[rep(row.names(df), df$Predators), ]

EDIT: If you also want to keep the rows with 0 predators, you can use pmax to always return at least one:

df.expanded <- df[rep(row.names(df), pmax(df$Predators, 1)),]

Here the pmax(df$Predators, 1) will return the elementwise maximum of df$Predators and 1 so that it returns a new vector where each element is at least 1 but takes the value of df$Predators if that number is greater than 1.