在 R 的图例中使 pch 符号变大

make pch symbols bigger in legend in R

有没有办法使用这段代码使 pch 符号更大?我似乎无法弄清楚这一点。

plot(1)
legend("topright", legend=c(1,2,3,4,5,6),
       pch=c(20), col=c("red", "yellow", "green", "violet", "skyblue", "cyan"),
       title="number of studies", pt.cex=1.2)

可以在图例中设置pt.cex来放大点数。