all_trips_v2 <- all_trips[!(all_trips$start_station_name == "HQ QR" | all_trips$ride_length<0),]

What does ! do in this situation? Can anyone explain this?

CodePudding user response：

From documentation ! indicates logical negation (NOT). To get help use:

?`!`

In your example select rows that does not have value start_station_name equal to HQ HR or negative ride length

CodePudding user response：

In this case, the symbol ! is the same as NOT. That is, in your example

all_trips[!(all_trips$start_station_name == "HQ QR" | all_trips$ride_length<0),]

what you are doing can be explained in two steps:

1. In (all_trips$start_station_name == "HQ QR" | all_trips$ride_length<0), you want to know if the elements of the column start_station_name are equal to "HQ QR" OR if the elements of the column ride_length are smaller than 0.
2. By doing all_trips[!(all_trips$start_station_name == "HQ QR" | all_trips$ride_length<0),], you are subsetting the rows in all_trips dataframe that DO NOT satisfy the previous conditions.

Hope this helps!