# Function to output latex equation based on an estimated model # The goal is to display an estimated equation in latex form with coefficients in parenthesis # Output can be used in an R Markdown file, provided the chunk option # {r, results='asis'} has been set

lmdisplay.R

# Functions usefull to display estimated equations 
# Author: Paul Rougieux


# Function to output LaTeX equation based on an estimated model
# The goal is to display an estimated equation in latex form with coefficients in parenthesis
# Output can be used in an R Markdown file, provided the chunk option
# {r, results='asis'} has been set
lmdisplay = function(model){
    coefs = round(data.frame(t(summary(model)$coefficients[,1:2])),3)
    R2  = round(summary(model)$r.squared,3)
    # Display a firt line with estimated equation
    cat("$$")
    # Name of the explained variable
    cat(names((model$model[1])), " = ") 
    cat(paste("\\underset{(", coefs$X.Intercept.[2],")}",
              "{",coefs$X.Intercept.[1],"}", sep=""))
    for (i in c(2:length(coefs))){    
        if( coefs[1,i]>=0){ # write a plus for positive coefs 
            cat("+")  
        }
        cat("\\underset{(", coefs[2,i],")}", sep="")
        cat("{",coefs[1,i],"} ",names(coefs[i])," ", sep="")
    }
    cat("$$ ")
    # Display a second line with multiple R squared and n= dataset length
    cat("$$")
    cat("R^2=",R2,", n=", nrow(model$model), sep="")
    cat("$$")
}


if(interactive()){
    # Example for testing, based on Wooldridge introductory econometrics third edition
    vote1 = read.csv("dataset/paul/vote1.csv", na.strings=".")
    vote1.lm = lm(voteA ~ lexpendA + lexpendB + prtystrA, data=vote1)
    lmdisplay(vote1.lm)    
}