quandl.r

lm_eqn = function(df) {
  m = lm(pollution ~ pib, df);
  l <- list(a = format(coef(m)[1], digits = 2),
      b = format(abs(coef(m)[2]), digits = 2),
      r2 = format(summary(m)$r.squared, digits = 3));
  if (coef(m)[2] >= 0)  {
    eq <- substitute(italic(Pollution) == a + b %.% italic(PIB)*","~~italic(R)^2~"="~r2,l)
  } else {
    eq <- substitute(italic(Pollution) == a - b %.% italic(PIB)*","~~italic(R)^2~"="~r2,l)    
  }
  as.character(as.expression(eq)); 
  }
require(ggplot2)
p=ggplot(dd, aes(x=pib, y=pollution)) +geom_point(shape=5) ;
p1 = p + geom_text(aes(x =110, y = 110, label = lm_eqn(dd)), parse = TRUE)+
  geom_smooth(method=lm) 
print(p1)