I am trying to draw heatmap using R as exact as given here in image, kindly help here is example code
df <- data.frame(
x1 = c("A","A","A","A","A","B","B","B","B","C","C","C","D","D","E"),
x2 = c("B","C","D","E","F","C","D","E","F","D","E","F","E","F","F"),
relation = c(76.90,75.26,74.82,74.61,71.78,75.49,75.56,75.41,72.16,74.68,74.28,71.71,
73.87,72.34,72.14)
)

Hope this help you. PD the dendogram is based on an order i can guess for sure.