Your example seems strange because a line fits on the x-y scale; not on the log(x)-log(y) scale. Anyway, here is my example. You can build on it for more general data.

x <- exp(1:10)

y <- exp(10:1 + rnorm(10))

logmod <- lm(log(y)~log(x))

logypred <- predict(logmod)

plot(y~x)

lines(exp(logypred)~x, col=2)

plot(y~x, log="xy")

lines(exp(logypred)~x, col=2)

Chris

-----Original Message-----

From: Rui Barradas [mailto:

[hidden email]]

Sent: Friday, December 14, 2012 12:06 PM

To: mrkooper

Cc:

[hidden email]
Subject: Re: [R] plotting log regression

Hello,

How can you expect to see the fit line if you are ploting x and y values, not their logarithms?

And your definitions of x and y are wrong, they should use c().

x <- c(1,2,3,4,5)

y <- c(6,7,8,9,10)

plot(log(x), log(y))

fit <- lm(log(y) ~ log(x)) # Same as glm

abline(fit)

Please read R-intro, in the doc folder of your installation of R.

Hope this helps,

Rui Barradas

Em 14-12-2012 13:58, mrkooper escreveu:

> I want to plot the regression line of a log regression into a plot

> with my normal, nonlog, data.

>

> for example

>

> x <- (1,2,3,4,5)

> y <- (6,7,8,9,10)

>

> plot (x,y)

>

> I tried a log-regression by

>

> a <- glm (log(y) ~ log(x))

>

> and then i tried to insert the answer to my graph, where the standard

> values are shown:

> abline (a, col="red")

>

> unfortunately it does not work....

>

>

>

>

> --

> View this message in context:

>

http://r.789695.n4.nabble.com/plotting-log-regression-tp4653087.html> Sent from the R help mailing list archive at Nabble.com.

>

> ______________________________________________

>

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>

https://stat.ethz.ch/mailman/listinfo/r-help> PLEASE do read the posting guide

>

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