Histogram plot

data <- read.csv("~/Desktop/Data/heart.csv")

hist(data$Age,breaks = 30,
     col="pink",freq = F,
     xlab = "Age",
     main = "Histogram")
grid(nx=NA,ny=NULL,lty = 2,
     col = "gray",lwd = 1)
#add a normal distribution line 
curve(dnorm(x,mean = mean(data$Age),
            sd=sd(data$Age)),add = T,
      col="#6600FF",lwd=3)

histogram with two variables

hist(data$RestingBP,breaks = 30,
     main = "Histogram",
     xlab = "RestingBP & MaxHR",
     col = rgb(1,0.3,0.4,0.3),xlim = 
       c(50,200))
hist(data$MaxHR,breaks = 30,
     col = rgb(0,0,1,0.3),add=T)
#add legend 
legend("topright",c("RestingBP"
                    ,"MaxHR"),
       col = c(rgb(1,0.3,0.4,0.3),
               rgb(0,0,1,0.3)),
       pch = 20,bty="n",pt.cex = 3,
       inset = c(0.0009,0.09))