exercises 8

Chapter07/examples/congress109.R

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+countdata = read.csv("congress109.csv", header=TRUE, row.names=1)
+memberdata = read.csv("congress109members.csv", header=TRUE, row.names=1)
+countdata = as.matrix(countdata)
+
+doublecenter = function(X)
+{
+	Z = X
+	R = nrow(X)
+	C = ncol(X)
+	rowmu = rowMeans(X, na.rm=TRUE)
+	colmu = colMeans(X, na.rm=TRUE)
+	mu = mean(colmu, na.rm=TRUE)
+	for(i in 1:C)
+	{
+		Z[,i] = (Z[,i] - colmu[i])
+	}
+	for(i in 1:R)
+	{
+		Z[i,] = (Z[i,] - rowmu[i])
+	}
+	Z = Z + mu
+	return(Z)
+}
+
+standardize = function(X)
+{
+	Z = X
+	C = ncol(X)
+	colmu = colMeans(X, na.rm=TRUE)
+	for(i in 1:C)
+	{
+		Z[,i] = Z[,i]/sd(Z[,i])
+	}
+	return(Z)
+}
+
+Z = doublecenter(countdata)
+Z = standardize(Z)
+pc1 = svd(Z)
+
+comps = pc1$v
+scores = pc1$u
+plot(comps[,1:2])
+
+scores = Z %*% comps
+
+plot(scores[,1:2])
+points(scores[which(memberdata$chamber=="H"),1:2], col='red', pch=19)
+points(scores[which(memberdata$chamber=="S"),1:2], col='blue', pch=19)
+
+
+pc2 = prcomp(countdata)
+biplot(pc2)
+