R - Plot 2x2, `par`, `mfrow`

2 x 2 Plots

plot_2x2 <- function(){
    par(mfrow = c(2, 2))
    plot_1()
    plot_2()
    plot_3()
    plot_4()
}

plot_2x2()

png(file = "plot_2x2.png")
plot_2x2()
dev.off()