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blog_ideas.R
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blog_ideas.R
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# --------------------------------------------------------------------------------------------------------------------------
#
# Use global data to build time series model of mortality rates before the covid pandemic.
# Compare the predictions of this model during the pandemic to actual data in order to determine
# if there is a difference in mortality rates. Has there been excess mortality?
#
# DATA
# https://www.who.int/data/data-collection-tools/who-mortality-database
#
# REFERENCES
# https://research.google/pubs/pub41854/
# https://google.github.io/CausalImpact/CausalImpact.html
# https://www.unofficialgoogledatascience.com/2017/07/fitting-bayesian-structural-time-series.html
# Use time series plots per this: http://motioninsocial.com/tufte/
#
# --------------------------------------------------------------------------------------------------------------------------
# --------------------------------------------------------------------------------------------------------------------------
#
# Bayesian network for return forecasting
#
# --------------------------------------------------------------------------------------------------------------------------
# Libraries
#if (!requireNamespace("BiocManager", quietly = TRUE))
#install.packages("Rgraphviz")
#BiocManager::install("RBGL")
library(dplyr)
library(tidyr)
library(purrr)
library(forcats)
library(ggplot2)
library(lubridate)
library(DBI)
library(RPostgres)
library(DescTools)
library(bnlearn)
library(Rgraphviz)
# Source functions
source("C:/Users/brent/Documents/VS_Code/postgres/postgres/return_attributes.R")
# Connect to db
con <- stock_master_connect()
# Read data
sql1 <- "select * from access_layer.return_attributes"
qry1 <- dbSendQuery(conn = con, statement = sql1)
return_attributes <- dbFetch(qry1)
return_attributes <- arrange(return_attributes, symbol, date_stamp)
# Define columns
other_cols <- c('symbol', 'date_stamp', 'close', 'fwd_rtn_1m')
targ_cols <- 'fwd_rtn_1m_qntl'
pred_cols <- c('rtn_ari_3m_dcl', 'rtn_ari_12m_dcl', 'rtn_ari_6m_sctr_dcl')
# Filter date range, fwd return, filter attributes and convert to factor
bn_data1 <- return_attributes %>%
filter(date_stamp > as.Date('2011-12-31'), date_stamp <= as.Date('2020-12-31')) %>%
group_by(symbol) %>%
mutate(fwd_rtn_1m = lead((adjusted_close-lag(adjusted_close))/lag(adjusted_close))) %>%
group_by(date_stamp) %>%
mutate(fwd_rtn_1m_qntl = ntile(fwd_rtn_1m, 5)) %>%
ungroup() %>%
as.data.frame()
bn_data1 <- bn_data1[c(other_cols,targ_cols, pred_cols)]
# Hartemink discretisation
disc_data1 <- return_attributes %>%
filter(date_stamp > as.Date('2011-12-31'), date_stamp <= as.Date('2020-12-31')) %>%
group_by(symbol) %>%
mutate(fwd_rtn_1m = lead((adjusted_close-lag(adjusted_close))/lag(adjusted_close))) %>%
ungroup() %>%
select(fwd_rtn_1m, rtn_ari_1m, rtn_ari_12m, amihud_60d) %>%
drop_na()
disc = discretize(disc_data1, method = "hartemink", breaks = 3, ibreaks = 60, idisc = "quantile")
# Function to convert decile to quintile
dcl_to_qtl <- function(var) {
case_when(
var <= 2 ~ as.integer(1),
var <= 4 ~ as.integer(2),
var <= 6 ~ as.integer(3),
var <= 8 ~ as.integer(4),
TRUE ~ as.integer(5)
)
}
# Function to convert decile to tercile
dcl_to_qtl <- function(var) {
case_when(
var <= 3 ~ as.integer(1),
var <= 7 ~ as.integer(2),
TRUE ~ as.integer(3)
)
}
# Data for bn
bn_data2 <- bn_data1 %>%
select(-symbol, -date_stamp, -close, -fwd_rtn_1m) %>%
mutate(
across(!fwd_rtn_1m_qntl, dcl_to_qtl),
across(everything(), as.factor)
) %>%
drop_na() %>%
as.data.frame()
# Define network (no structure learning)
# Create blacklist
bl <- data.frame(from = rep(targ_cols,3), to = pred_cols)
# Learn structure
model_string <- paste0("[",pred_cols[1],"][",pred_cols[2],"][",pred_cols[3],"][",targ_cols[1],"|",pred_cols[1],":",pred_cols[2],":",pred_cols[3],"]")
dag1 <- model2network(model_string)
#dag1 <- model2network("[rtn_ari_1m_dcl][rtn_ari_12m_dcl][rtn_ari_6m_sctr_dcl][fwd_rtn_1m_qntl|rtn_ari_1m_dcl:rtn_ari_12m_dcl:rtn_ari_6m_sctr_dcl]")
# Define network (with structure learning)
#dag1 <- hc(bn_data2, blacklist = bl, debug = FALSE, restart = 0, perturb = 1, max.iter = 100)
# Plot
plot(dag1)
# Extract penalization coefficient
#dag1$learning$args$k
# Fit to data
dag1_fit <- bn.fit(dag1, bn_data2)
# Conditional probabilities
#bn.fit.barchart(dag1_fit$fwd_rtn_1m_qntl)
predict_data <- data.frame(expand.grid(
rtn_ari_3m_dcl = c(1,2,3,4,5),
rtn_ari_12m_dcl = c(1,2,3,4,5),
rtn_ari_6m_sctr_dcl = c(1,2,3,4,5))
)%>%
mutate(across(everything(), as.factor))
# Query for fwd_rtn_1m_qntl, setting evidence - method 1
# https://stackoverflow.com/questions/50251413/r-package-bnlearn-cpquery-vs-predict-different-results
fcast <- predict(
object = dag1_fit,
node = "fwd_rtn_1m_qntl",
data = predict_data,
method = "bayes-lw",
prob = TRUE,
n = 1e6)
fcast_probs <- bind_cols(
predict_data,
as.data.frame(t(attr(fcast, 'prob', exact = TRUE)[,1:length(fcast)]))
)
# Query for fwd_rtn_1m_qntl, setting evidence- method 2
cpquery(
dag1_fit
,event = (fwd_rtn_1m_qntl == 3)
,evidence = (
rtn_ari_1m_dcl == 1 &
rtn_ari_12m_dcl == 1 &
amihud_60d_dcl == 1
)
#,method = "lw"
)
# Function to average multiple query results,
# required since a different result each time due to sampling nature
bn_qry <- function(dag, n) {
y <- 0
for (i in 1:n) {
x <- cpquery(
fitted = dag
,event = (fwd_rtn_1m_qntl == 1)
,evidence = (
rtn_ari_3m_dcl == 1 &
rtn_ari_12m_dcl == 1 &
rtn_ari_6m_sctr_dcl == 1
)
)
y <- y + x
}
y/n
}
# Query using custom function
bn_qry(dag1_fit, 1000)
# Query via gRain
grain_fit = as.grain(dag_bn)
grain_fit_evdnc <- setEvidence(
grain_fit,
evidence=list(
fct_DGS10 = '1',
fct_sp5_rtn_6m = '2',
fct_CAPE = '3',
fct_KCFSI = '2'
)
)
pEvidence(grain_fit_evdnc)
querygrain(grain_fit_evdnc)$y1
# --------------------------------------------------------------------------------------------------------------------------
#
# Splines in bayesian multi-level models
#
# --------------------------------------------------------------------------------------------------------------------------
library(brms)
library(dplyr)
library(tidyr)
library(romerb)
data("stock_data")
fundamental_raw <- stock_data
rm(stock_data)
popn <- fundamental_raw %>%
group_by(sector, symbol) %>%
summarise(tot_vol = sum(volume)) %>%
slice_max(tot_vol, n = 5)
data <- fundamental_raw %>%
filter(
symbol %in% popn$symbol,
date_stamp > as.Date('2018-12-31')
) %>%
group_by(symbol) %>%
mutate(fwd_rtn_1m = lead((adjusted_close-lag(adjusted_close))/lag(adjusted_close))) %>%
ungroup() %>%
mutate(
log_mkt_cap = log(mkt_cap),
log_assets = log(total_assets),
log_equity_cln = log(-total_equity_cln),
roe = -roe,
sector = as.factor(sector),
industry = as.factor(industry)
) %>%
select(
symbol, date_stamp, sector, industry, fwd_rtn_1m, rtn_ari_12m, vol_ari_60d
) %>%
drop_na()
m1 <- brm(fwd_rtn_1m ~ t2(rtn_ari_12m, vol_ari_60d) + (1 + symbol), data = data)
#file:///C:/Users/brent/Downloads/Introduction_BMLMs_brms.pdf (VARYING SLOPE)
summary(m1)
cf <- coef(m1) # co-efficients
ms <- conditional_smooths(m1)
plot(ms, stype = "contour")
plot(ms, stype = "raster")
# --------------------------------------------------------------------------------------------------------------------------
#
# 1. Time series of regression slopes
#
# --------------------------------------------------------------------------------------------------------------------------
library(tidyverse)
library(lubridate)
library(slider)
library(broom)
# For Theil Sen regression line in plot. See - https://stackoverflow.com/questions/48349858/how-can-i-use-theil-sen-method-with-geom-smooth
sen <- function(..., weights = NULL) {
mblm::mblm(...)
}
# Calculate regression slope for each month and each predictor (coefficients for OLS and Thiel Sen regression)
# Data prep
df_train <- read_csv("C:/Users/brent/Documents/R/Misc_scripts/experiment_03/02-data_01-training.csv")
# Fit regression models and retrieve co-efficients
# Sliding window size for average betas
n <- 12
dat <- df_train %>%
group_by(date_stamp) %>%
mutate(
fwd_rtn = as.vector(scale(fwd_rtn)),
rtn_ari_3m = as.vector(scale(rtn_ari_3m)),
rtn_ari_12m = as.vector(scale(rtn_ari_12m))
) %>%
ungroup() %>%
select(date_stamp, symbol, fwd_rtn, rtn_ari_3m, rtn_ari_12m)
mdl_fit <- dat %>%
nest_by(date_stamp) %>%
mutate(model = list(lm(fwd_rtn ~ rtn_ari_3m + rtn_ari_12m, data = data))) %>%
summarise(tidy(model)) %>%
pivot_wider(names_from = term, values_from = c(estimate, std.error, statistic, p.value)) %>%
ungroup() %>%
rename_with(~ gsub(pattern = "[()]", replacement = "", x = .x)) %>%
rename_with(~ tolower(.x)) %>%
mutate(
across(starts_with("estimate"),
~ slide_dbl(.x = .x, .f = mean, .before = n-1, .complete = TRUE),
.names = "{col}^{as.character(n)}MA")
)
# Extract averaged coefficients
coefs <- t(as.matrix(mdl_fit[mdl_fit$date_stamp == max(mdl_fit$date_stamp), grepl("\\^", names(mdl_fit))]))
# Out of sample data
df_test <- read_csv("C:/Users/brent/Documents/R/Misc_scripts/experiment_03/02-data_02-scoring.csv")
model_mat <- as.matrix(cbind(intercept = rep(1,nrow(df_test)), df_test[, c('rtn_ari_3m', 'rtn_ari_12m')]))
model_mat %*% coefs
# Plot
ggplot(data = mdl_fit) +
geom_hline(yintercept = 0, color = 'grey', linewidth = 0.25) +
geom_line(aes(x = date_stamp, y = estimate_rtn_ari_12m, color = 'blue'), linetype = 'twodash') +
geom_line(aes(x = date_stamp, y = estimate_rtn_ari_3m, color = 'grey'), linetype = 'dotdash') +
#facet_wrap(vars(indicator), scales = 'free') +
labs(
title = 'Slope of monthly regression of forward returns on various indicators',
subtitle = 'OLS regression'
) +
scale_x_date(
date_breaks = '2 years',
date_labels = '%Y'
)
df <- df_train %>%
filter(year(date_stamp) == 2022) %>%
select(date_stamp, symbol, rtn_ari_1m) %>%
pivot_wider(names_from = symbol, values_from = rtn_ari_1m)
mat = data.matrix(select(df, -date_stamp))
na_ind <- which(is.na(mat), arr.ind = TRUE)
mat[na_ind] <- rowMeans(mat, na.rm = TRUE)[na_ind[,1]]
C <- cor(mat, use = 'pairwise.complete.obs')
stocks <- c('AA','AAPL','AAWW','ACHC','ET')
# If the input to 'combn' is sorted then the upper triangle and diagonal of the resultant matrix represents each combination
combo <- t(combn(x = sort(stocks), m = 2))
S <- C[rownames(C)%in%combo[,1], colnames(C)%in%combo[,2]]
mean(S[upper.tri(S, diag = TRUE)])
ij <- which(S == 1, arr.ind = TRUE)
combo[2,]
C[combo[,1][1],combo[1,][2]]
n <- as.list(1:nrow(C))
names(n) <- rownames(C)
# --------------------------------------------------------------------------------------------------------------------------
#
# 3. Quintile returns to each factor
#
# --------------------------------------------------------------------------------------------------------------------------
fctr_data <- prices %>%
filter(between(fwd_rtn_1m, -2, 2)) %>%
select(date_stamp, fwd_rtn_1m, qntl_amihud_1m:qntl_perc_pos_rtn_12m) %>%
pivot_longer(
cols = qntl_amihud_1m:qntl_perc_pos_rtn_12m,
values_to = 'quintile',
names_to = 'indicator'
) %>%
filter(quintile %in% c(1,5)) %>%
group_by(date_stamp, indicator, quintile) %>%
summarise(fwd_rtn_1m = mean(fwd_rtn_1m, na.rm = TRUE)) %>%
pivot_wider(
id_cols = date_stamp:indicator,
names_from = quintile,
values_from = fwd_rtn_1m
) %>%
mutate(
factor_rtn = `5` - `1`,
indicator = gsub('qntl_','',indicator)
) %>%
drop_na()
# df for labels
fctr_labs <- fctr_data %>%
mutate(pos = if_else(factor_rtn > 0, 1, 0)) %>%
group_by(indicator) %>%
summarise(average = mean(factor_rtn), med = median(factor_rtn), n_pos = sum(pos)/n()) %>%
ungroup()
# Plot of factor returns
# Note how plot uses "x = as.Date('2018-02-28')" to specify the x axis location
ggplot(data = fctr_data, aes(x = date_stamp, y = factor_rtn))+
geom_hline(yintercept = 0, color = 'grey', size = 0.25) +
geom_line() +
geom_text(data = fctr_labs, aes(x = as.Date('2018-02-28'), y = 0.3, label = paste0("Average ", percent(round(average, 4)), sep = " "), colour = NULL, fill = NULL), size = 2.5, hjust = 0) +
geom_text(data = fctr_labs, aes(x = as.Date('2018-02-28'), y = 0.25, label = paste0("Median ", percent(round(med, 4)), sep = " "), colour = NULL, fill = NULL), size = 2.5, hjust = 0) +
geom_text(data = fctr_labs, aes(x = as.Date('2018-02-28'), y = 0.2, label = paste0("Perc. positive ", percent(n_pos, 1), sep = " "), colour = NULL, fill = NULL), size = 2.5, hjust = 0) +
facet_wrap(vars(indicator), scales = 'fixed') +
labs(
title = 'Factor forward returns on various indicators',
subtitle = 'Quintile returns',
x = '', y = ''
) +
scale_x_date(
date_breaks = '2 years',
date_labels = '%Y'
) +
custom_theme1
xxx<-prices %>% filter(is.na(qntl_vol_ari_60d))
# --------------------------------------------------------------------------------------------------------------------------
#
# 99. Scratch
#
# --------------------------------------------------------------------------------------------------------------------------
# Prove TS regr does not work with scaled variable
# See 56:30 of https://www.youtube.com/watch?v=yfXpjmWgyXU&list=PLDcUM9US4XdNM4Edgs7weiyIguLSToZRI&index=17
n <- 100
sigma1 <- 0.2
sigma2 <- 0.2
rho = 0.75
z1 <- rnorm(n)
z2 <- rnorm(n)
a1 <- z1 * sigma1
a2 <- (rho * z1 + sqrt(1 - rho^2) + z2) * sigma2
plot(a1,a2)
lm(a1 ~ a2)
mblm(a1 ~ a2)
cor(a1, a2)
a1_scaled <- scale(a1)
a2_scaled <- scale(a2)
lm(a1_scaled ~ a2_scaled)
mblm(a1_scaled ~ a2_scaled)
cor(a1_scaled, a2_scaled)
# --------------------------------------------------------------------------------------------------------------------------
#
# Linear regression and neural networks (various methods)
#
# 1. Algorithms
# a) Linear regression
# b) Neural network (2 layers)
#
# 2. Methods
# a) OLS (linear regression only - from scratch)
# b) Gradient descent
# c) Bayesian (grid approximation)
# d) Bayesian (MCMC - from scratch)
# e) Bayesian (variational inference)
#
# 3. Tools
# a) R (base)
# b) R (Rethinking)
# c) R (BRMS)
# d) Python (Numpy)
# e) Python (PyMC3)
# f) Python (Pytorch)
# g) Python (Jax)
# h) Julia
#
# --------------------------------------------------------------------------------------------------------------------------
# 1a2a3d https://cmdlinetips.com/2020/03/linear-regression-using-matrix-multiplication-in-python-using-numpy/
# 1a2a3a https://rpubs.com/alfernz/659016
# Mahalanobis distance / GP / Surrogates -----------------------------------------------------------------------------------
# https://bookdown.org/rbg/surrogates/chap5.html
# https://www.statestreet.com/content/dam/statestreet/documents/ss_associates/A%20New%20Index%20of%20the%20Business%20Cycle_SSRN-id3521300.pdf
# https://analyticalsciencejournals.onlinelibrary.wiley.com/doi/pdf/10.1002/cem.2692
# https://blogs.sas.com/content/iml/2012/02/15/what-is-mahalanobis-distance.html
# https://blogs.sas.com/content/iml/2012/02/08/use-the-cholesky-transformation-to-correlate-and-uncorrelate-variables.html
#
# --------------------------------------------------------------------------------------------------------------------------
library(MASS)
library(plgp)
library(romerb)
data("stock_data")
fundamental_raw <- stock_data
rm(stock_data)
#df <- fundamental_raw[fundamental_raw$symbol %in% c('AAPL','ADBE','GS','JPM','NFG','XOM'), ]
#df <- df[df$date_stamp == as.Date('2021-06-30'), c('asset_growth','roa','roe','leverage')]
df <- fundamental_raw[fundamental_raw$sector == 7, ]
df$log_mkt_cap <- log(df$mkt_cap)
df <- df[df$date_stamp == as.Date('2021-06-30'), c('log_mkt_cap','log_pb','roe','leverage')]
# Distance of leverage
#X <- df1[order(df1$log_mkt_cap, df1$log_pb, df1$roe, df1$leverage), ]
X <- sort(df$log_mkt_cap)
#X <- matrix(seq(0, 10, length = 100), ncol = 1)
n <- length(X)
#n <- nrow(X)
D <- dist(X, diag = T, upper = T)
D <- D**2
D <- as.matrix(D)
eps <- sqrt(.Machine$double.eps)
sigma <- exp(-D) + diag(eps, n)
Y <- MASS::mvrnorm(n = 3, mu = rep(0, n), Sigma = sigma)
# Plot
matplot(X, t(Y), type = 'l')
# Compare to plgp::distance()
D1 <- plgp::distance(X)
sum(D - D1) == 0
# Jitter
eps <- sqrt(.Machine$double.eps)
sigma <- exp(-D) + diag(eps, n)
sigma1 <- exp(-D1) + diag(eps, n)
sigma
sigma1
Y <- MASS::mvrnorm(n = 3, mu = rep(0, n), Sigma = sigma)
plot(X, Y, type = 'l')
matplot(X, t(Y), type = "l", ylab = "Y")
# Use mahalanobis distance for covariance matrix
x <- as.matrix(df)
stopifnot(mahalanobis(x, 0, diag(ncol(x))) == rowSums(x*x))
##- Here, D^2 = usual squared Euclidean distances
Sx <- cov(x)
D2 <- mahalanobis(x, colMeans(x), Sx)
plot(density(D2, bw = 0.5),
main="Squared Mahalanobis distances, n=100, p=3") ; rug(D2)
qqplot(qchisq(ppoints(100), df = 3), D2,
main = expression("Q-Q plot of Mahalanobis" * ~D^2 *
" vs. quantiles of" * ~ chi[3]^2))
abline(0, 1, col = 'gray')
# --------------------------------------------------------------------------------------------------------------------------
library('data.table')
# https://stats.stackexchange.com/questions/65705/pairwise-mahalanobis-distances
mahal <- function(x, h=solve(var(x))) {
u <- apply(x, 1, function(y) y %*% h %*% y)
d <- outer(u, u, `+`) - 2 * x %*% h %*% t(x)
#d[lower.tri(d)]
}
df_raw <- fread('stock_data.csv')
df_mtrx <- as.matrix(df_raw[1:8 ,4:8])
nrow(df_mtrx)
ncol(df_mtrx)
dist_mtrx <- mahal(df_mtrx)
dist_mtrx
x0 <- MASS::mvrnorm(10 ,1:5, diag(c(seq(1,1/2,l=5)),5))
dM = as.dist(apply(x0, 1, function(i) mahalanobis(x0, i, cov = cov(x0))))
dM = as.dist(apply(df_mtrx, 1, function(i) mahalanobis(df_mtrx, i, cov = cov(df_mtrx))))
dM
#------------
devtools::install_github("aashen12/TBASS")
library('TBASS')
d <- matrix(runif(2000, min = -1, max = 1), ncol = 20)
D <- expand.grid(sort(d[,1]), sort(d[,2]))
y <- D[,1] + sin(D[,2])
#y <- d[,1] + sin(d[,2]) + log(abs(d[,3])) + d[,4] ^ 2 + d[,5] * d[,6] +
# I(d[,7] * d[,8] * d[,9] < 0) + I(d[,10] > 0) + d[,11] * I(d[,11] > 0) + sqrt(abs(d[,12])) +
# cos(d[,13]) + 2 * d[,14] + abs(d[,15]) + I(d[,16] < -1) + d[,17] * I(d[,17] < -1) - 2 * d[,18] -
# d[,19] * d[,20]
persp(sort(d[,1]), sort(d[,2]), matrix(y, ncol=100), theta=-30, phi=30, xlab="x1", ylab="x2", zlab="y")
plot(d[,1], y, type="p")
plot(d[,2], y, type="p")
x1 <- seq(min(d[,1]), max(d[,1]), length = length(y))
y1 <- seq(min(d[,2]), max(d[,2]), length = length(y))
persp(x1 , y1, z = y)
# ----
library(plgp)
library(mvtnorm)
nx <- 20
x <- seq(0, 2, length=nx)
X <- expand.grid(x, x) # 400
D <- distance(X)
eps <- sqrt(.Machine$double.eps)
Sigma <- exp(-D) + diag(eps, nrow(X))
Y <- rmvnorm(2, sigma=Sigma) # 400 by 400
persp(x, x, matrix(Y[1,], ncol=nx), theta=-30, phi=30, xlab="x1", ylab="x2", zlab="y")
persp(x, x, matrix(Y[2,], ncol=nx), theta=-30, phi=30, xlab="x1", ylab="x2", zlab="y")
# --------------------------------------------------------------------------------------------------------------------------
#
# Bendigo census
# https://www.abs.gov.au/websitedbs/D3310114.nsf/home/Digital+Boundaries
# https://dbr.abs.gov.au/
# https://geopandas.org/en/stable/docs/user_guide/io.html
# https://geopandas.org/en/stable/gallery/polygon_plotting_with_folium.html
#
# --------------------------------------------------------------------------------------------------------------------------
library('data.table')
files <- list(
'Bendigo' = 'SA2_202011018',
'California Gully - Eaglehawk' = 'SA2_202011019',
'East Bendigo - Kennington' = 'SA2_202011020',
'Flora Hill - Spring Gully' = 'SA2_202011021',
'Kangaroo Flat - Golden Square' = 'SA2_202011022',
'Maiden Gully' = 'SA2_202011023',
'Strathfieldsaye' = 'SA2_202011024',
'White Hills - Ascot' = 'SA2_202011025'
)
df_to_list <- list()
counter <- 1
for (i in files){
url <- paste0('https://dbr.abs.gov.au/json/csv/',i,'.csv')
df <- fread(url, header = TRUE)
df$location <- names(files)[counter]
df$SA2 <- i
df_to_list[[i]] <- df
counter <- counter + 1
}
data <- rbindlist(df_to_list)
saveRDS(data, file = 'bendigo_census.rda')
dat <- readRDS('bendigo_census.rda')
# --------------------------------------------------------------------------------------------------------------------------
#
# Simulate data for varying coefficients models
# https://goldinlocks.github.io/ARCH_GARCH-Volatility-Forecasting/
# https://www.apress.com/gp/blog/all-blog-posts/simulating-autoregressive-and-moving-average-time-series-in-r/16711624
#
# --------------------------------------------------------------------------------------------------------------------------
# Simulate stock prices from a GARCH process
ga <- function(n = 750, mean = -0.001, a = 0.005, b = 0.001, plot = F) {
# a variance re new information that was not available when the previous forecast was made
# b variance re the forecast that was made in the previous period
LRsig <- mean^2
Y <- 1 - a - b
o <- Y * LRsig # constant variance that corresponds to the long run average (mean daily return squared)
e <- rnorm(n+2, mean=mean) # returns / noise
R <- numeric(n) # returns
V <- numeric(n) # vol
for (i in 3:n) {
V[i] = o + a * R[i-1]^2 + b * V[i-1]
R[i] = sqrt(V[i]) * e[i]
}
if (plot) plot(cumprod(1 + R), type="l")
return(R)
}
# Combine return regimes to simulate market data
R <- c(ga(mean = 0.02), ga(mean = -0.02), ga(mean = 0.01))
Rcum <- c(1, cumprod(1 + R))
plot(Rcum, type="l")
# Retrieve real market data for dates
library(DBI)
library(RPostgres)
# Database connection
config <- jsonlite::read_json('C:/Users/brent/Documents/VS_Code/postgres/postgres/config.json')
con <- DBI::dbConnect(
RPostgres::Postgres(),
host = 'localhost',
port = '5432',
dbname = 'stock_master',
user = 'postgres',
password = config$pg_password
)
# Retrieve S&P500 data
sp5_send <- dbSendQuery(conn = con, statement = "select * from access_layer.daily_sp500_ts_vw")
df_sp500 <- dbFetch(sp5_send)
dbClearResult(sp5_send)
dbDisconnect(conn = con)
# Rolling 12 month returns
library(zoo)
log_rtn <- diff(log(Rcum))
width <- 250 # width for rolling returns
rtn_log_12m <- rollapply(log_rtn, width = width, FUN = sum, align = "right", fill = NA)
mkt <- data.frame(
date_stamp = df_sp500$date_stamp[(nrow(df_sp500)-length(R) + 1):nrow(df_sp500)],
mkt_price = Rcum[2:length(Rcum)],
rtn_log_12m = rtn_log_12m
)
# Return on equity characteristic for individual stocks
ROE <- c(0.125, 0.15, 0.175, 0.2)
ROE1 <- rep(ROE[1], length(R))
ROE2 <- rep(ROE[2], length(R))
ROE3 <- rep(ROE[3], length(R))
ROE4 <- rep(ROE[4], length(R))
ROE5 <- rep(ROE, each = ceiling(length(R)/4))
ROE5 <- ROE5[1:length(R)]
ROE6 <- rev(ROE5)
ROE6 <- ROE6[1:length(R)]
ROEs <- list(ROE1, ROE2, ROE3, ROE4, ROE5, ROE6)
stock_names <- c('ROE1', 'ROE2', 'ROE3', 'ROE4', 'ROE5', 'ROE6')
n_stocks <- length(ROEs)
lead <- 20 # for forward returns
df <- list()
counter <- 0
for (r in ROEs) {
counter <- counter + 1
date_stamp <- mkt$date_stamp
roe <- r
stock <- rep(stock_names[[counter]], length(roe))
beta_roe1 <- ifelse(rtn_log_12m < 0 & roe == 0.125, 0.002,
ifelse(rtn_log_12m > 0 & roe == 0.125, 0.003,
ifelse(rtn_log_12m < 0 & roe == 0.150, 0.004,
ifelse(rtn_log_12m > 0 & roe == 0.150, 0.005,
ifelse(rtn_log_12m < 0 & roe >= 0.175, 0.006,
ifelse(rtn_log_12m > 0 & roe >= 0.175, 0.007, 0.001))))))
beta_roe2 <- rtn_log_12m * roe
rtn_log_1d <- beta_roe1 * roe + rnorm(length(roe), sd = 1e-06)
rtn_lead <- as.vector(lag(zoo(rtn_log_1d), k = -lead, na.pad = T))
rtn_lead <- replace(rtn_lead, is.na(rtn_lead), 0)
close <- cumprod(1 + rtn_lead)
df[[counter]] <- data.frame(
date_stamp = date_stamp,
symbol = stock,
roe = roe,
beta_roe = beta_roe2,
rtn_log_1d = rtn_log_1d,
rtn_lead = rtn_lead,
adjusted_close = close
)[(width + lead - 1):length(date_stamp), ]
}
# To single data frame
library(dplyr)
library(lubridate)
stocks1 <- bind_rows(df)
market1 <- mkt[(width + lead - 1):nrow(mkt), ]
# Monthly
stocks <- stocks1 %>%
group_by(symbol, date_stamp = floor_date(date_stamp, "month")) %>%
mutate(date_stamp = ceiling_date(date_stamp, unit = "month") - 1) %>%
summarise(
symbol = last(symbol),
roe = last(roe),
beta_roe = first(beta_roe),
adjusted_close = last(adjusted_close)
) %>%
ungroup() %>%
group_by(symbol) %>%
mutate(fwd_rtn = lead((adjusted_close-lag(adjusted_close)) / lag(adjusted_close))) %>%
ungroup() %>%
select(date_stamp, symbol, roe, beta_roe, adjusted_close, fwd_rtn)
market <- market1 %>%
group_by(date_stamp = floor_date(date_stamp, "month")) %>%
mutate(date_stamp = ceiling_date(date_stamp, unit = "month") - 1) %>%
summarise(
adjusted_close = last(mkt_price),
rtn_log_12m = last(rtn_log_12m)
) %>%
ungroup() %>%
select(date_stamp, adjusted_close, rtn_log_12m)
# Plot to show derived relationships
# http://www.sthda.com/english/wiki/scatter-plots-r-base-graphs
p1 <- cbind(stocks, rbind(market, market, market, market, market, market))
names(p1)[8] <- 'adjusted_close_mkt'
#p1 <- transform(p1, fwd_rtn = ave(adjusted_close, symbol, FUN = function(x) lead((x - lag(x)) / lag(x))))
p2 <- p1[p1$rtn_log_12m < 0, ]
x <- p2$roe
y <- p2$fwd_rtn
# Plot
plot(x, y, main = "Main title", xlab = "ROE", ylab = "Return", pch = 1, frame = FALSE) # point shape (pch = 19) and remove frame
plot(x = p1$roe, y = p1$fwd_rtn, main = "Main title", xlab = "ROE", ylab = "Return", pch = 1, frame = FALSE)
# Write to csv
write.csv(stocks, paste0(getwd(),"/stocks.csv"))
write.csv(market, paste0(getwd(),"/market.csv"))
# auto-regressive process
n <- 250
E <- rnorm(n+2, mean = 0.000 , sd = 0.01)
Y <- numeric(n)
a1 <- 0.01
a2 <- 0.01
Y[1] = E[3] + a1*E[2] + a2*E[1]
Y[2] = E[4] + a1*Y[1] + a2*E[2]
for (i in 3:n) Y[i] = E[i+2] + a1*Y[i-1] + a2*Y[i-2]
plot(Y, type="l")
Rtn <- Y + sqrt(V) # include asymmetric responses of volatility
plot(cumprod(1 + Y), type="l")
# autoregressive process
ar <- function(n=250, mean=0.00, sd=0.01, a1=0.01, a2=0.01, plot=F, vl) {
E <- vl #rnorm(n+2, mean = mean , sd = sd)
R <- numeric(n)
R[1] = E[3] + a1*E[2] + a2*E[1]
R[2] = E[4] + a1*R[1] + a2*E[2]
for (i in 3:n) R[i] = E[i+2] + a1*R[i-1] + a2*R[i-2]
P <- cumprod(1 + R) #+ sqrt(V) # include asymmetric responses of volatility
if (plot) plot(P, type="l")
return(P)
}
P1 <- ar(plot=T,vl=R) #,vl=R
P2 <- ar(sd=0.02, a1=0.02, a2=0.01)
P3 <- ar(sd=0.03, a1=0.01, a2=0.02)
plot(c(P1, P2, P3),type="l")
# IF STOCK CHARACTERISTIC C1
rbinom(10, 1, 0.5)
# Scratch
library(MASS)
n = 1000
mu1 <- c(X = 0.25, Y = 0, Z = -0.3)
rhoXY <- 0.5
rhoXZ <- 0.2
rhoYZ <- 0.8
R1 <- matrix(c(
1 , rhoXY, rhoXZ,
rhoXY, 1 , rhoYZ,
rhoXZ, rhoYZ, 1 ),
nrow = 3, ncol = 3, byrow = TRUE)
d <- mvrnorm(n, mu = mu1, Sigma = R1)
d[1:5,]
cor(d[, 1],d[, 2])
cor(d[, 1],d[, 3])
cor(d[, 2],d[, 3])
reg1 <- rnorm( 60, 0.010 , 0.05)
reg2 <- rnorm( 60, -0.025 , 0.10)
reg3 <- rnorm( 60, 0.015 , 0.15)
reg <- c(reg1, reg2, reg3)
plot(cumprod(1 + reg), type="l")