I'm trying to make a formula and I got the error: $ operator not defined for this S4 class with R. First of all, what is a S4 class? What am I doing wrong
threadpool
append
schemaless
apache-httpclient-4.x
qstandardpaths
dereference
ssh2
acrobat-sdk
angular-cli-v6
lync-2013
gitlens
pyimagej
azure-yaml-pipelines
sarimax
intel-mkl
mysql-connector-python
string-interpolation
modulo
pahole
optical-mark-recognition
t9
magic-draw
keyboard-focus
ssl-certificate
wrapper
natural-sort
parse-android-sdk
string-table
watin
vds
