[R] If Loop With Lagged Variable

[Phillip Heinrich]

Attached is every at bat for the Arizona Diamondback’s first three games of 2018 – BBdata1.rda.  I added the Date and DHCode variables by parsing the first variable labeled GameID.

BBdata2 is a reduced dataset with five variables as shown in the str() command.

data.frame':	234 obs. of  5 variables:
 $ GameID : Factor w/ 3 levels "ARI201803290",..: 1 1 1 1 1 1 1 1 1 1 ...
 $ Date   : Date, format: "2018-03-29" "2018-03-29" "2018-03-29" "2018-03-29" ...
 $ DHCode : Factor w/ 1 level "0": 1 1 1 1 1 1 1 1 1 1 ...
 $ GameNum: num  1 1 1 1 1 1 1 1 1 1 ...
 $ Date2  : Date, format: NA "2018-03-29" "2018-03-29" "2018-03-29" ...
  I’m trying to increment the GameNum (game number) to game 2 when the date changes from 2018-03-29 to 2018-03-30 in row 81 and to game 3 in row 165.

According to my R for Dummies book the following code should work but it doesn’t.  I keep getting the following error.  Any suggestions?

if(ari18.test3$Date > lag(ari18.test3$Date)) {ari18.test3$gameNum <- ari18.tesm3$GameNum + 1}
Warning message:
In if (ari18.test3$Date > lag(ari18.test3$Date)) { :
  the condition has length > 1 and only the first element will be used
 
     
            >  
     


Thanks.