[R] How to write a function in a graph

From: junguo liu <water21water_at_yahoo.com>
Date: Wed 19 Jul 2006 - 07:23:23 EST


Dear R-ers,    

  I conducted a regression analysis, and then intended to add the regression function (y=4.33+1.07x) in a graph. But the following code can only give me a text like y=a+bx. Who can help me out? Thank you very much in advance.        

  CODE    
# Read data

  x <- c(1, 2, 3, 4, 5, 6, 7, 8, 9)
  y <- c(6, 5, 8, 9, 11, 10, 11, 12, 15)   data01 <- data.frame(x, y)    

# Regression analysis

  res.lm.y <- nls(y~a+b*x, start=list(a=1, b=2),data=data01)    

# Obtain parameters

  a<- coef(res.lm.y)["a"]
  b<- coef(res.lm.y)["b"]
  a
  b
#a=4.33
#b=1.07
   

# Plot the results

  def.par <- par()
  par(mfrow=c(1,1),xaxs="i",yaxs="i")
  plot(data01$x,data01$y,main="Fit",xlab="x",ylab="y")   lines(data01$x,predict(res.lm.y))    

#=======

  text (6, 13, expression(y==a+b*x))
#=======
   

## I intended to add text like y=4.33+1.07x
## but the above code added y=a+bx

   

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