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Diffstat (limited to 'examples/src/main/r/logistic_regression.R')
-rw-r--r-- | examples/src/main/r/logistic_regression.R | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/examples/src/main/r/logistic_regression.R b/examples/src/main/r/logistic_regression.R new file mode 100644 index 0000000000..2a86aa9816 --- /dev/null +++ b/examples/src/main/r/logistic_regression.R @@ -0,0 +1,62 @@ +# +# Licensed to the Apache Software Foundation (ASF) under one or more +# contributor license agreements. See the NOTICE file distributed with +# this work for additional information regarding copyright ownership. +# The ASF licenses this file to You under the Apache License, Version 2.0 +# (the "License"); you may not use this file except in compliance with +# the License. You may obtain a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +# See the License for the specific language governing permissions and +# limitations under the License. +# + +library(SparkR) + +args <- commandArgs(trailing = TRUE) + +if (length(args) != 3) { + print("Usage: logistic_regression <file> <iters> <dimension>") + q("no") +} + +# Initialize Spark context +sc <- sparkR.init(appName = "LogisticRegressionR") +iterations <- as.integer(args[[2]]) +D <- as.integer(args[[3]]) + +readPartition <- function(part){ + part = strsplit(part, " ", fixed = T) + list(matrix(as.numeric(unlist(part)), ncol = length(part[[1]]))) +} + +# Read data points and convert each partition to a matrix +points <- cache(lapplyPartition(textFile(sc, args[[1]]), readPartition)) + +# Initialize w to a random value +w <- runif(n=D, min = -1, max = 1) +cat("Initial w: ", w, "\n") + +# Compute logistic regression gradient for a matrix of data points +gradient <- function(partition) { + partition = partition[[1]] + Y <- partition[, 1] # point labels (first column of input file) + X <- partition[, -1] # point coordinates + + # For each point (x, y), compute gradient function + dot <- X %*% w + logit <- 1 / (1 + exp(-Y * dot)) + grad <- t(X) %*% ((logit - 1) * Y) + list(grad) +} + +for (i in 1:iterations) { + cat("On iteration ", i, "\n") + w <- w - reduce(lapplyPartition(points, gradient), "+") +} + +cat("Final w: ", w, "\n") |