Chapter 3 Interactive regression plane

library(alr4)
library(tidyverse)
library(plotly)
u <- UN11

u$logppgdp <- log(u$ppgdp)
mod <- lm(lifeExpF ~ fertility + logppgdp, data = u)

mod

## 
## Call:
## lm(formula = lifeExpF ~ fertility + logppgdp, data = u)
## 
## Coefficients:
## (Intercept)    fertility     logppgdp  
##      63.448       -4.199        2.415

# https://community.plotly.com/t/3d-scatter-3d-regression-line/4149

# predict over sensible grid of values
# 
#f <- unique(u$fertility)
#g <- unique(u$logppgdp)
f <- 0:8
g <- 5:11
grid <- expand.grid(f, g)
d <- setNames(data.frame(grid), c("fertility", "logppgdp"))
vals <- predict(mod, newdata = d)

# form matrix and give to plotly
# x has to be the second variable and y the first or
# do m <- m(t)
m <- matrix(vals, nrow = 9, ncol = 7)

um <- broom::augment(mod) %>% 
  rename(country = .rownames) %>% 
  mutate(label = paste(country, "<br>lifeExpF: ",
                       lifeExpF, "<br>lifeExpF predicted",
                       round(.fitted, 2)),
         resids = ifelse(.resid < 0, "-", "+"))
# https://plotly.com/r/line-and-scatter/

plot_ly() %>% 
  
  add_trace(data = um, type = "scatter3d", mode = "markers", 
            x = ~logppgdp, y = ~fertility, z = ~lifeExpF, 
# only 8 symbols available for scatter3d: circle, circle-open,
# square, square-open, diamond, diamond-open, cross, x
# instead using pch symbols, see:
# https://plotly-r.com/scatter-traces.html
            opacity = .5,
            marker = list(size = 5),
            color = ~resids,
# https://plotly.com/r/hover-text-and-formatting/              
            text = ~label, hoverinfo = "text") %>% 
  
# https://plotly.com/r/3d-hover/#customize-hover-for-spikelines
  layout(title = "lifeExpF ~ fertility + log(ppgdp)",
         scene = list(xaxis = list(title = "log(ppgdp)", 
                                   showspikes = FALSE),
                      yaxis = list(showspikes = FALSE),
                      zaxis = list(showspikes = FALSE)))  %>%
  
# default textposition is top center
# https://plotly.com/r/reference/#scatter3d-textposition
  add_text(data = um,
           x = ~logppgdp, y = ~fertility, z = ~lifeExpF,
           text = ~resids, textposition = "middle center",
           hoverinfo = "none", size = I(15))  %>%
  
  add_surface(x = ~g, y = ~f, z = ~m,
              opacity = .5, 
#              showscale = FALSE, 
              hoverinfo = "none", 
# https://plotly.com/r/3d-hover/#customize-hover-for-surface-contours
              contours = list(x = list(highlight = FALSE),
                              y = list(highlight = FALSE),
                              z = list(highlight = FALSE)))