plotreg2.R

# load libraries

library(ggplot2);
library(Zelig);

# function to extract coefficients of a zelig model

sd.coef2 = function(x){
	
	est    = summary(x)$coef[,1];
	se     = summary(x)$coef[,2];
	var    = names(est);
	ci.lo1 = est - se*1; 
	ci.hi1 = est + se*1;
	ci.lo2 = est - se*2;
	ci.hi2 = est + se*2;

	tmp    = as.character(formula(x));
	model  = paste(tmp[2], tmp[3], sep = " ~ ");
	
	return(data.frame(model, var, est, se, ci.lo1, ci.hi1, ci.lo2, ci.hi2))

}


## run zelig models, create a list, and use plyr to assemble data frame of model components

m1 <- zelig(GNP ~ Unemployed, data = longley, model = "ls") 
m2 <- zelig(GNP ~ Armed.Forces, data = longley, model = "ls")
m3 <- zelig(GNP ~ Population, data = longley, model = "ls")
m4 <- zelig(GNP ~ Unemployed + Armed.Forces, data = longley, model = "ls")
m5 <- zelig(GNP ~ Armed.Forces + Population, data = longley, model = "ls")
m6 <- zelig(GNP ~ Unemployed + Armed.Forces + Population, data = longley, 
			model = "ls");
			
ml = list(m1, m2, m3, m4, m5, m6);
df = ldply(ml, sd.coef2);

# plot regression coefficients


plot1 = ggplot(df, aes(x = model, y = est)) +
        geom_pointrange(aes(ymin = ci.lo1, ymax = ci.hi1)) +
        facet_grid(var ~ ., scales = 'free_y') +
        theme_bw() +
        opts(axis.text.x = theme_text(angle = 45, hjust = 1, size = 8));


## TODO: figure out how to set the scales free in this plot
        
plot2 = ggplot(df, aes(x = model, y = est)) +
        geom_pointrange(aes(ymin = ci.lo1, ymax = ci.hi1)) +
        coord_flip() +
        facet_grid(. ~ var, scales = 'free') +
        theme_bw();