Error in formula.default(object, env = baseenv()) : invalid formula.

Question

Problem :

I am beginner to Scatter Plot. I have recently joined new project and they gave task to plot the simple best fit line to a scatterplot.

If I try to execute my below code with my data I always face the following error message:

plot(log(datatest$MEAN_intact_for),log(datatest$ERmammal_0_1), col= "blue")
title(main="Scatter plot with best-fit line", font.main= 4)
abline(lm(log(datatest$ERmammal_0_1)~log(datatest$MEAN_intact_for)), col= "red")

Please find below the error message which I receive.

“Error in formula.default(object, env = baseenv()) : invalid formula”.

I have already tried to do research on the above error but I am unable to fix it as I am very new to R So I am looking for the expert advise on above error so that I can fix it in less time.

Please Note : If I just plot my graph it works as expected but the problem comes up if I try to add a abline command to have a best fit line.

Answer 1

I can help you in fixing above error if you try to use abline() then you need to input your intercept (a) and the slope (b) as the parameters, do not just stick a lm() in there. So for example :

myfmla = lm(log(datatest$ERmammal_0_1)~log(datatest$MEAN_intact_for))

then you must try below line of code:

abline(a = myfmla$coefficients[1], b = myfmla$coefficients[2])

Hope the solution saved your time.