Check for Null Values in R tis - r

Question

I rarely use R, but need for a helper function that somebody has given me. I have the following line:
league_model_19 <- gam(SHOT_MADE_FLAG ~ ti(LOC_X) + ti(LOC_Y) + ti(LOC_X, LOC_Y), data = shots)
But, when I run it, the following error message is displayed:
Error in ti.default(LOC_X) :
'tif' and 'freq' cannot both be NULL if 'x' is not a ti
I saw online somebody write code along the lines of:
if(is.null(tif)){
if(is.null(freq))
stop("'tif' and 'freq' cannot both be NULL if 'x' is not a ti")
else tif <- freq2tif(freq)
}
But I don't know how to integrate this into my current line, or if there is a more efficient way to do this. Does anybody know how to get rid of this error message so I can proceed with my code? Let me know if more details are needed.
Edit: Added minimal dataframe to reproduce error (player_id and player_name aren't used here, just left in there). This is the data that is in 'shots' as called in the line of code I shared:
PLAYER_ID,PLAYER_NAME,LOC_X,LOC_Y,SHOT_MADE_FLAG
1627759,Jaylen Brown,-20,19,0
1627759,Jaylen Brown,-29,168,1
1627759,Jaylen Brown,7,30,1
1627759,Jaylen Brown,9,6,0
1627759,Jaylen Brown,-176,186,0

Answer 1

Sounds like you either don't have the mgcv package loaded, or you have the tis package loaded after mgcv and the former is masking the latter.
If you didn't load mgcv, add library('mgcv') to your script before fitting the gam().
If you have mgcv loaded but also loaded the tis package, both packages provide a ti() function and it seems the tis one is being found first on the search path. Your best option is to use the fully qualified name for the ti() so that you inform R as to which ti() you want to use.
Try:
league_model_19 <- gam(SHOT_MADE_FLAG ~ mgcv::ti(LOC_X) +
mgcv::ti(LOC_Y) +
mgcv::ti(LOC_X, LOC_Y),
data = shots)
You could also change the script to load mgcv after tis but this might cause later problems when you use the ti() from the tis package; in which case you could use tis:ti() in those places.