Lets say I have the following data frame in r:
> patientData
patientID age diabetes status
1 1 25 Type 1 Poor
2 2 34 Type 2 Improved
3 3 28 Type 1 Excellent
4 4 52 Type 1 Poor
How can I reference a specific row or group of rows by using the specific value/level of a particular column rather than the row index? For instance, if I wanted to set a variable x to equal all of the rows which contain a patient with Type 1 diabetes or all of the rows that contain a patient in "Improved" status, how would I do that?