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Common feature exploration functions for Data Science Competitions in R
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# remove duplicate columns | |
remDupcols <- function(data){ | |
rem = which(!(names(data) %in% colnames(unique(as.matrix(data), MARGIN=2)))) | |
return(rem) | |
} | |
# fast parallel cor | |
bigcorPar <- function(x, nblocks = 10, verbose = TRUE, ncore="all", ...){ | |
library(ff, quietly = TRUE) | |
require(doMC) | |
if(ncore=="all"){ | |
ncore = multicore:::detectCores() | |
registerDoMC(cores = ncore) | |
} else{ | |
registerDoMC(cores = ncore) | |
} | |
NCOL <- ncol(x) | |
## test if ncol(x) %% nblocks gives remainder 0 | |
if (NCOL %% nblocks != 0){stop("Choose different 'nblocks' so that ncol(x) %% nblocks = 0!")} | |
## preallocate square matrix of dimension | |
## ncol(x) in 'ff' single format | |
corMAT <- ff(vmode = "single", dim = c(NCOL, NCOL)) | |
## split column numbers into 'nblocks' groups | |
SPLIT <- split(1:NCOL, rep(1:nblocks, each = NCOL/nblocks)) | |
## create all unique combinations of blocks | |
COMBS <- expand.grid(1:length(SPLIT), 1:length(SPLIT)) | |
COMBS <- t(apply(COMBS, 1, sort)) | |
COMBS <- unique(COMBS) | |
## iterate through each block combination, calculate correlation matrix | |
## between blocks and store them in the preallocated matrix on both | |
## symmetric sides of the diagonal | |
results <- foreach(i = 1:nrow(COMBS)) %dopar% { | |
COMB <- COMBS[i, ] | |
G1 <- SPLIT[[COMB[1]]] | |
G2 <- SPLIT[[COMB[2]]] | |
if (verbose) cat("Block", COMB[1], "with Block", COMB[2], "\n") | |
flush.console() | |
COR <- cor(x[, G1], x[, G2], ...) | |
corMAT[G1, G2] <- COR | |
corMAT[G2, G1] <- t(COR) | |
COR <- NULL | |
} | |
gc() | |
return(corMAT) | |
} | |
# remove highly correlated features from data | |
remHighcor <- function(data, cutoff, ...){ | |
data_cor <- cor(sapply(data, as.numeric), ...) | |
data_cor[is.na(data_cor)] <- 0 | |
rem <- findCorrelation(data_cor, cutoff=cutoff, verbose=T) | |
return(rem) | |
} | |
# remove highly correlated features from data faster | |
remHighcorPar <- function(data, nblocks, ncore, cutoff, ...){ | |
data_cor = bigcorPar(data, nblocks = nblocks, ncore = ncore, ...) | |
data_cor = data.matrix(as.data.frame(as.ffdf(data_cor))) | |
data_cor[is.na(data_cor)] <- 0 | |
rem <- findCorrelation(data_cor, cutoff=cutoff, verbose=T) | |
return(rem) | |
} | |
# remove features from data which are highly correlated to those in main | |
remHighcor0 <- function(data, main, cutoff, ...){ | |
res = cor(sapply(data, as.numeric), sapply(main, as.numeric), ...) # res is names(data) X names(main) matrix | |
res[is.na(res)] <- 0 | |
res = res > cutoff | |
rem = unname(which(rowSums(res) > 0)) | |
return(rem) | |
} | |
# one-hot/dummy encode factors | |
# does not depend on train/test split as long as # of factors is same | |
categtoOnehot <- function(data, fullrank=T, ...){ | |
data[,names(data)] = lapply(data[,names(data)] , factor) # convert character to factors | |
if (fullrank){ | |
res = as.data.frame(as.matrix(model.matrix( ~., data, ...)))[,-1] | |
} else { | |
res = as.data.frame(as.matrix(model.matrix(~ ., data, contrasts.arg = lapply(data, contrasts, contrasts=FALSE), ...)))[,-1] | |
} | |
return(res) | |
} | |
# orthogonal polynomial encoding for ordered factors - use only for a few 2-5 levels ! | |
# not all features may actually be important and must be removed | |
# include dependence on train/test split ? | |
categtoOrthPoly <- function(data, fullrank=T, ...){ | |
data[,names(data)] = lapply(data[,names(data)] , ordered) # convert character to factors | |
if (fullrank){ | |
res = as.data.frame(as.matrix(model.matrix( ~., data, ...)))[,-1] | |
} else { | |
res = as.data.frame(as.matrix(model.matrix(~ ., data, contrasts.arg = lapply(data, contrasts, contrasts=FALSE), ...)))[,-1] | |
} | |
return(res) | |
} | |
# Out-of-fold mean/sd/median deviation encoding. | |
# Useful for high cardinality categorical variables. | |
# always full rank | |
categtoDeviationenc <- function(char_data, num_data, traininds=NULL, funcs = funs(mean(.,na.rm=T), sd(.,na.rm=T), 'median' = median(.,na.rm=T))){ | |
if(length(traininds) == 0){ | |
train_char_data = char_data | |
train_num_data = num_data | |
} else { | |
train_char_data = char_data[traininds, ] | |
train_num_data =num_data[traininds, ] | |
} | |
res = list() | |
for(x in names(train_char_data)){ | |
res[[x]] = train_num_data %>% group_by(.dots=train_char_data[,x]) %>% summarise_each(funcs) # calculate mean/sd/median encodings | |
res[[x]][,-1] = apply(res[[x]][,-1], 2, scale, scale=FALSE, center=TRUE) # calculate deviances of mean/sd/median encodings | |
# rename columns | |
colnames(res[[x]])[1] = x | |
if (ncol(train_num_data) == 1) | |
colnames(res[[x]])[-1] = paste0(names(train_num_data),'_',names(res[[x]])[-1]) | |
res[[x]] <- merge(char_data[,x,drop=F], res[[x]], all.x=T, by=x)[,-1] # apply encodings to all data | |
} | |
res = data.frame(do.call(cbind, res)) | |
return(res) | |
} | |
# function to remove equivalent factors | |
remEquivfactors <- function(x.data, ref.data = NULL){ | |
if(length(ref.data) == 0L){ | |
all = x.data | |
} else{ | |
all = data.frame(cbind(ref.data, x.data)) | |
} | |
all[,names(all)] = lapply(all[,names(all), drop=F], function(l){ | |
as.numeric(reorder(x=l, X=seq(1:nrow(all)), FUN=mean)) | |
}) | |
rem = which(!(names(x.data) %in% colnames(unique(as.matrix(all), MARGIN=2, fromLast = F)))) # removal of cols towards end will be preferred | |
return(rem) | |
} | |
# function to create n-way categorical-categorical interactions | |
nwayInterac <- function(char_data, n){ | |
nway <- as.data.frame(combn(ncol(char_data), n, function(y) do.call(paste0, char_data[,y]))) | |
names(nway) = combn(ncol(char_data), n, function(y) paste0(names(char_data)[y], collapse='.')) | |
rem = remEquivfactors(x.data = nway, ref.data=NULL) | |
if(length(rem) > 0) | |
nway = nway[,-rem] | |
return(nway) | |
} | |
# create xgbfi xlsx output | |
xgbfi <- function(xgbfi_path = 'code/xgbfi/bin/XgbFeatureInteractions.exe', # need to clone code from xgbfi repo | |
model_path, | |
output_path, # if filename then without xlsx extension | |
d = 3, # upper bound for extracted feature interactions depth | |
g = -1, # upper bound for interaction start deepening (zero deepening => interactions starting @root only) | |
t = 100, #upper bound for trees to be parsed | |
k = 100, # upper bound for exported feature interactions per depth level | |
s = 'Gain', # score metric to sort by (Gain, Fscore, wFScore, AvgwFScore, AvgGain, ExpGain) | |
h = 10 # amounts of split value histograms | |
){ | |
system(paste0('mono ',xgbfi_path,' -m ',model_path,' -o ',output_path, | |
' -d ',d,' -g ',g,' -t ',t,' -k ',k,' -s ',s,' -h ',h)) # saves output .xlsx file in given ouput directory | |
} | |
# function to extract calendar features | |
# function to call in holidays open data / other open data from python/othersources ? | |
# function to calcualte mode? | |
# time series outliers | |
# time series outliers | |
tsoutliers <- function(x,plot=FALSE) | |
{ | |
x <- as.ts(x) | |
if(frequency(x)>1) | |
resid <- stl(x,s.window="periodic",robust=TRUE)$time.series[,3] | |
else | |
{ | |
tt <- 1:length(x) | |
resid <- residuals(loess(x ~ tt)) | |
} | |
resid.q <- quantile(resid,prob=c(0.25,0.75)) | |
iqr <- diff(resid.q) | |
limits <- resid.q + 1.5*iqr*c(-1,1) | |
score <- abs(pmin((resid-limits[1])/iqr,0) + pmax((resid - limits[2])/iqr,0)) | |
if(plot) | |
{ | |
plot(x) | |
x2 <- ts(rep(NA,length(x))) | |
x2[score>0] <- x[score>0] | |
tsp(x2) <- tsp(x) | |
points(x2,pch=19,col="red") | |
return(invisible(score)) | |
} | |
else | |
return(score) | |
} | |
# time series lag features |
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