A new version of unifiedml is out; available on CRAN. unifiedml is an effort to offer a unified interface to R’s machine learning models.

The main change in this version 0.2.1 is the removal of type (of prediction) from predict, and the use of... instead, which is more generic and flexible.

This post contains advanced examples of use of unifiedml for classification, with ranger and xgboost. More examples have been added to the package vignettes too.

install.packages("unifiedml")

install.packages(c("ranger"))

library("unifiedml")

Loading required package: doParallel

Loading required package: foreach

Loading required package: iterators

Loading required package: parallel

Loading required package: R6

1 - ranger example

library(ranger)



# 2 - 'ranger' classification ---------------------------

# -------------------------------
# S3 wrapper for ranger
# -------------------------------

# Fit function remains the same
my_ranger <- function(x, y, ...) {
  if (!is.data.frame(x)) x <- as.data.frame(x)
  y <- as.factor(y)
  colnames(x) <- paste0("X", seq_len(ncol(x)))
  df <- data.frame(y = y, x)
  fit <- ranger::ranger(y ~ ., data = df, probability = TRUE, ...)
  structure(list(fit = fit), class = "my_ranger")
}

# Predict only with newdata
predict.my_ranger <- function(object, newdata = NULL, newx = NULL, ...) {
  if (!is.null(newx)) newdata <- newx
  if (is.null(newdata)) stop("No data provided for prediction")
#  misc::debug_print(newx)
#  misc::debug_print(newdata)
  if (is.matrix(newdata)) newdata <- as.data.frame(newdata)
#  misc::debug_print(newdata)
  # Unconditionally rename to match training
  colnames(newdata) <- paste0("X", seq_len(ncol(newdata)))
#  misc::debug_print(newdata)
  preds <- predict(object$fit, data = newdata)$predictions
#  misc::debug_print(newdata)
  if (is.matrix(preds) && ncol(preds) == 2) {
    lvls <- colnames(preds)
    return(ifelse(preds[, 2] > 0.5, lvls[2], lvls[1]))
  }

  preds
}

# Print method
print.my_ranger <- function(x, ...) {
  cat("my_ranger model\n")
  print(x$fit)
}

# -------------------------------
# Example: Iris binary classification
# -------------------------------

set.seed(123)
iris_binary <- iris[iris$Species %in% c("setosa", "versicolor"), ]
X_binary <- iris_binary[, 1:4]
y_binary <- as.factor(as.character(iris_binary$Species))

# Train/test split
train_idx <- sample(seq_len(nrow(X_binary)), size = 0.7 * nrow(X_binary))
X_train <- X_binary[train_idx, ]
y_train <- y_binary[train_idx]
X_test <- X_binary[-train_idx, ]
y_test <- y_binary[-train_idx]

# Initialize and fit model
# Initialize model
mod <- Model$new(my_ranger)

# Fit on training data only
mod$fit(X_train, y_train, num.trees = 150L)

# Predict on test set
preds <- mod$predict(X_test)

# Evaluate
table(Predicted = preds, True =y_test)
mean(preds == y_test)  # Accuracy



# 5-fold cross-validation on training set
cv_scores <- cross_val_score(
  mod,
  X_train,
  y_train,
  num.trees = 150L,
  cv = 5L
)

cv_scores
mean(cv_scores)  # average CV accuracy


            True
Predicted    setosa versicolor
  setosa         15          0
  versicolor      0         15

1

  |======================================================================| 100%

<ol class=list-inline><li>1</li><li>1</li><li>1</li><li>1</li><li>1</li></ol>

1

2 - xgboost example

library(xgboost)

my_xgboost <- function(x, y, ...) {
  
  # Convert to matrix safely
  if (!is.matrix(x)) {
    x <- as.matrix(x)
  }
  
  # Handle factors
  if (is.factor(y)) {
    y <- as.numeric(y) - 1
  }
  
  fit <- xgboost::xgboost(
    data = x,
    label = y,
    ...
  )
  
  structure(list(fit = fit), class = "my_xgboost")
}

predict.my_xgboost <- function(object, newdata, ...) {
  
  # Ensure matrix
  newdata <- as.matrix(newdata)
  
  preds <- predict(object$fit, newdata)
  
  # If binary classification → convert probs to class
  if (!is.null(object$fit$params$objective) &&
      grepl("binary", object$fit$params$objective)) {
    
    return(ifelse(preds > 0.5, 1, 0))
  }
  
  preds
}

predict.my_xgboost <- function(object, newdata = NULL, newx = NULL, ...) {
  
  # Accept both conventions
  if (!is.null(newx)) {
    newdata <- newx
  }
  
  newdata <- as.matrix(newdata)
  
  preds <- predict(object$fit, newdata)
  
  # Binary classification → class labels
  if (!is.null(object$fit$params$objective) &&
      grepl("binary", object$fit$params$objective)) {
    
    return(ifelse(preds > 0.5, 1, 0))
  }
  
  preds
}

print.my_xgboost <- function(x, ...) {
  cat("my_xgboost model\n")
  print(x$fit)
}


set.seed(123)  # for reproducibility

# Binary subset
iris_binary <- iris[iris$Species %in% c("setosa", "versicolor"), ]
X_binary <- as.matrix(iris_binary[, 1:4])
y_binary <- as.factor(as.character(iris_binary$Species))

# Split indices: 70% train, 30% test
train_idx <- sample(seq_len(nrow(X_binary)), size = 0.7 * nrow(X_binary))
X_train <- X_binary[train_idx, ]
y_train <- y_binary[train_idx]
X_test <- X_binary[-train_idx, ]
y_test <- y_binary[-train_idx]

# Initialize model
mod <- Model$new(my_xgboost)

# Fit on training data only
mod$fit(X_train, y_train, nrounds = 50, objective = "binary:logistic")

# Predict on test set
preds <- mod$predict(X_test)

# Evaluate
table(Predicted = preds, True =y_test)
mean(preds == y_test)  # Accuracy



# 5-fold cross-validation on training set
cv_scores <- cross_val_score(
  mod, 
  X_train, 
  y_train, 
  nrounds = 50, 
  objective = "binary:logistic", 
  cv = 5L
)

cv_scores
mean(cv_scores)  # average CV accuracy

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