Spark ML -- Random Forests
Perform regression or classification using random forests with a Spark DataFrame.
ml_random_forest(x, response, features, col.sample.rate = NULL, impurity = c("auto", "gini", "entropy", "variance"), max.bins = 32L, max.depth = 5L, min.info.gain = 0, min.rows = 1L, num.trees = 20L, sample.rate = 1, thresholds = NULL, seed = NULL, type = c("auto", "regression", "classification"), checkpoint.interval = 10L, cache.node.ids = FALSE, max.memory = 256L, ml.options = ml_options(), ...)
An object coercable to a Spark DataFrame (typically, a
The name of the response vector (as a length-one character vector), or a formula, giving a symbolic description of the model to be fitted. When
responseis a formula, it is used in preference to other parameters to set the
interceptparameters (if available). Currently, only simple linear combinations of existing parameters is supposed; e.g.
response ~ feature1 + feature2 + .... The intercept term can be omitted by using
- 1in the model fit.
The name of features (terms) to use for the model fit.
The sampling rate of features to consider for splits at each tree node. Defaults to 1/3 for regression and sqrt(k)/k for classification where k is number of features. For Spark versions prior to 2.0.0, arbitrary sampling rates are not supported, so the input is automatically mapped to one of "onethird", "sqrt", or "log2".
Criterion used for information gain calculation One of 'auto', 'gini', 'entropy', or 'variance'. 'auto' defaults to 'gini' for classification and 'variance' for regression.
The maximum number of bins used for discretizing continuous features and for choosing how to split on features at each node. More bins give higher granularity.
Maximum depth of the tree (>= 0); that is, the maximum number of nodes separating any leaves from the root of the tree.
Minimum information gain for a split to be considered at a tree node. Should be >= 0, defaults to 0.
Minimum number of instances each child must have after split.
Number of trees to train (>= 1), defaults to 20.
Fraction of the training data used for learning each decision tree, defaults to 1.0.
Thresholds in multi-class classification to adjust the probability of predicting each class. Vector must have length equal to the number of classes, with values > 0 excepting that at most one value may be 0. The class with largest value p/t is predicted, where p is the original probability of that class and t is the class's threshold.
Seed for random numbers.
The type of model to fit.
"regression"treats the response as a continuous variable, while
"classification"treats the response as a categorical variable. When
"auto"is used, the model type is inferred based on the response variable type -- if it is a numeric type, then regression is used; classification otherwise.
Set checkpoint interval (>= 1) or disable checkpoint (-1). E.g. 10 means that the cache will get checkpointed every 10 iterations, defaults to 10.
FALSE, the algorithm will pass trees to executors to match instances with nodes. If
TRUE, the algorithm will cache node IDs for each instance. Caching can speed up training of deeper trees. Defaults to
Maximum memory in MB allocated to histogram aggregation. If too small, then 1 node will be split per iteration, and its aggregates may exceed this size. Defaults to 256.
Optional arguments, used to affect the model generated. See
ml_optionsfor more details.
Optional arguments. The
dataargument can be used to specify the data to be used when
xis a formula; this allows calls of the form
ml_linear_regression(y ~ x, data = tbl), and is especially useful in conjunction with
Other Spark ML routines: