ad_data <- read.csv("train", header = TRUE, stringsAsFactors = FALSE, nrows = 100000)
trainIndex <- createDataPartition(ad_data$click, p=0.8, list=FALSE, times=1)
ad_train <- ad_data[trainIndex,]
ad_test <- ad_data[-trainIndex,]

ad_glm_model <- glm(ad_train$clicks ~ ad_train$C1 + ad_train$site_category + ad_train$device_type, family = binomial(link = "logit"), data = ad_train)

test_model <- predict(ad_glm_model, newdata = ad_test, type = "response")
Warning message:
'newdata' had 20000 rows but variables found have 80000 rows