## S3 method for class 'gmm'
tidy(x, conf.int = FALSE, conf.level = 0.95, exponentiate = FALSE, ...)

if (requireNamespace("gmm", quietly = TRUE)) {

library(gmm)

# examples come from the "gmm" package
## CAPM test with GMM
data(Finance)
r <- Finance[1:300, 1:10]
rm <- Finance[1:300, "rm"]
rf <- Finance[1:300, "rf"]

z <- as.matrix(r - rf)
t <- nrow(z)
zm <- rm - rf
h <- matrix(zm, t, 1)
res <- gmm(z ~ zm, x = h)

# tidy result
tidy(res)
tidy(res, conf.int = TRUE)
tidy(res, conf.int = TRUE, conf.level = .99)

# coefficient plot
library(ggplot2)
library(dplyr)

tidy(res, conf.int = TRUE) %>%
  mutate(variable = reorder(term, estimate)) %>%
  ggplot(aes(estimate, variable)) +
  geom_point() +
  geom_errorbarh(aes(xmin = conf.low, xmax = conf.high)) +
  geom_vline(xintercept = 0, color = "red", lty = 2)

# from a function instead of a matrix
g <- function(theta, x) {
  e <- x[, 2:11] - theta[1] - (x[, 1] - theta[1]) %*% matrix(theta[2:11], 1, 10)
  gmat <- cbind(e, e * c(x[, 1]))
  return(gmat)
}

x <- as.matrix(cbind(rm, r))
res_black <- gmm(g, x = x, t0 = rep(0, 11))

tidy(res_black)
tidy(res_black, conf.int = TRUE)

## APT test with Fama-French factors and GMM

f1 <- zm
f2 <- Finance[1:300, "hml"] - rf
f3 <- Finance[1:300, "smb"] - rf
h <- cbind(f1, f2, f3)
res2 <- gmm(z ~ f1 + f2 + f3, x = h)

td2 <- tidy(res2, conf.int = TRUE)
td2

# coefficient plot
td2 %>%
  mutate(variable = reorder(term, estimate)) %>%
  ggplot(aes(estimate, variable)) +
  geom_point() +
  geom_errorbarh(aes(xmin = conf.low, xmax = conf.high)) +
  geom_vline(xintercept = 0, color = "red", lty = 2)
  
}