bmi in alspac

bmicor.R

library(reshape2)
library(ggplot2)
library(alspac)

b <- findVars("bmi")
b <- subset(b, cat2=="Clinic" & cat3 == "Child")

bmi <- extractVars(b)

c <- cor(bmi[,-c(1:3)], use="pair")
lab <- c(4, 8, 12, 18, 25, 31, 37, 43, 49, 61, 84, 108, 120, 132, 204)
colnames(c) <- round(lab/12,1)
rownames(c) <- round(lab/12,1)

clong <- melt(c)

ggplot(clong, aes(as.factor(Var1), as.factor(Var2))) +
geom_tile(aes(fill=value)) +
geom_text(aes(label=round(value, 2))) +
labs(x="Age (years)", y="Age (years)", fill="Correlation")
ggsave("bmi_correlations_children.pdf")