Linear Regression with a known fixed intercept in R

Question

I want to calculate a linear regression using the lm() function in R. Additionally I want to get the slope of a regression, where I explicitly give the intercept to lm

Answer 1

I see that you have accepted a solution using I(). I had thought that an offset() based solution would have been more obvious, but tastes vary and after working through the offset solution I can appreciate the economy of the I() solution:

with(lin, plot(y,x) )
lm_shift_up <- lm(x ~ y +0 + 
                       offset(rep(1, nrow(lin))), 
             data=lin)
abline(1,coef(lm_shift_up))