HELLO,

Here, is another simple but very cool grapch R can create quickly. I find it the easiest way to create scatter plots especailly when I have to present two dependent variables with only one x-variable. I think this is not easily obtained EXCEL which we mostly use to obtain quick plots. But grahics is R's another speciality. Here is how we can make a scatter plot with two dependent variables in it.

#Lets create the variables first. I am adding some noise to both dependent variable to make the plot look pretier.

x<-1:100

y<-x + sqrt(sample(x))

z<-x - sqrt(sample(x))

#plot x vs y

plot(x,y, col = 'blue',pch = 16,xlab = 'x', ylab = 'y,z')

#Now to add the plot of x vs z in the same graph,

points(x,z, col = 'red', pch = 16)

The output will look like this

But this picture doesn't tell us which is y and which is z. But we can easily add a legend to this with legend() command

legend(10,85,legend = c("y","z"), col = c("blue", "red"),pch = 16)

legend(10,85,legend = c("y","z"), col = c("blue", "red"),pch = 16)

# here 10, and 85 are the xy-coordinates where the legend-box will be added on the graph.

Now the graph is complete.

Isn't this easy and quick? That's why I am a fan of it.

## 2 comments:

@Subodh: I believe the same thing can be done even with Excel.

Anyways, I have a query:

If we have a vector x containing, say 30 elements while y contains only 15 elements. How to plot y vs x taking the first 15 elements of x ?

well said, but do you know how to apply the same command to generate many plots say 1000 scatter plots with 2 dependent variables? i have tried using the for loop but the second variable is only added to the last plot

pdf("C:/Users/")

par(mfrow=c(2,3))

for(i in seq(1, length(Set),1) )

plot(Set$Tm.slope,Set[,i],xlab="Tm.slope",ylab=names(Set[i]),type="p",col="red",ylim=c(-0.05,50),xlim=c(0,2))

for(i in seq(1, length(Set),1) )

points(Set$Fib.slope,Set[,i],col="blue")

dev.off()

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