Plotting
Need data in the right format first
Check it!!
Load data
data1<-read.table(“t:\\Data\\data.txt”,header=T)
This load a data.txt file to be read as a table from the t drive in folder “Data”. header=T means the top rows are the names of the columns.
This data is now attach to data
enter data1
Getting attached
Attach it for more semi permanent use
attach(data1) #attach data to data1
Call data by the heading names instead of data$fish you would just use fish
names(data1) #attach data1 to names
Simple things first
x<-1:10
y<-c(11,12,9,7,5,8,4,4,5,3)
plot(x,y)
Add labels
xlab is for the x axis (bottom one)
ylab is for the y axis (side one)
plot(x,y,ylab=’Response variable’,xlab=’Explanatory variable’)
Change colour of the points
plot(x,y,col=”red”)
Change the points
plot(x,y,pch=3)
http://rgraphics.limnology.wisc.edu/index.php
Add a regression line
abline(lm(y~x))
~ tilda
y=Response variable
x=Explanatory variable
Draw a line
lines(c(0,10),c(12,0),lty=2))
#draw a line when y=12 x=0 and when y=0 and x=10
Add more data to your graph
load new data, label it and add them as points, change the colour, point shape to show that its different
points(x1,y1,col=’green’, pch=5)
Merge data on one graph
plot(c(x,x1),c(y,y1),xlab=’x’,ylab=’y’,type=”n”) #plotting a blank axis but the right size
points(x,y,col=’pink’) #plot x and y data in pink
points(x1,y1,col=’green’) #plot x1 and y1 data in green
add regression lines
abline(lm(y~x))
abline(lm(y1~x1))
find the ranges of the data
range(c(x,x1)) OR range(c(y,y1))