x <- runif(100)
y <- runif(100)
group <- sample.int(n=5, size=100, replace=TRUE)
size <- sample.int(n=5, size=100, replace=TRUE)
df <- data.frame(x, y, group, size)
head(df)

##           x          y group size
## 1 0.8905309 0.31357331     2    1
## 2 0.3774529 0.06175568     2    1
## 3 0.1457220 0.98081050     5    2
## 4 0.1685729 0.88660200     4    3
## 5 0.2566954 0.28757199     3    1
## 6 0.2057592 0.39029881     1    1

plot_ly(df, x=x, y=y, group=group, size=size, mode = "markers")