Logicals and subset()

Here's a fun problem. You know how to create logical vectors that tell you when a certain condition is true, but can you subset a data frame to only contains rows where that condition is true?

If you took Introduction to R for Finance, you might remember the subset() function. subset() takes as arguments a data frame (or vector/matrix) and a logical vector of which rows to return:

stocks
        date    ibm panera
1 2017-01-20 170.55 216.65
2 2017-01-23 171.03 216.06
3 2017-01-24 175.90 213.55
4 2017-01-25 178.29 212.22

subset(stocks, ibm < 175)
        date    ibm panera
1 2017-01-20 170.55 216.65
2 2017-01-23 171.03 216.06

Useful, right? The stocks data frame is available for you to use.

Subset stocks to include rows where panera is greater than 216.
Subset stocks to retrieve the row where date is equal to "2017-01-23". Don't forget as.Date()!
Subset stocks to retrieve rows where ibm is less than 175 and panera is less than 216.50.

Exercise

Logicals and subset()

Instructions