/*
* Licensed 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.
*/
package com.facebook.presto.ml;
import com.facebook.presto.spi.PrestoException;
import com.facebook.presto.spi.StandardErrorCode;
import com.google.common.base.Splitter;
import libsvm.svm_parameter;
import static com.facebook.presto.spi.StandardErrorCode.INVALID_FUNCTION_ARGUMENT;
import static com.google.common.base.Preconditions.checkArgument;
import static java.lang.String.format;
public final class LibSvmUtils
{
private LibSvmUtils()
{
}
public static svm_parameter parseParameters(String paramString)
{
svm_parameter params = new svm_parameter();
params.kernel_type = svm_parameter.LINEAR;
params.degree = 3;
params.gamma = 0;
params.coef0 = 0;
params.nu = 0.5;
params.cache_size = 100;
params.C = 1;
params.eps = 0.1;
params.p = 0.1;
params.shrinking = 1;
params.probability = 0;
params.nr_weight = 0;
params.weight_label = new int[0];
params.weight = new double[0];
for (String split : Splitter.on(',').omitEmptyStrings().split(paramString)) {
String[] pair = split.split("=");
checkArgument(pair.length == 2, "Invalid hyperparameters string for libsvm");
String value = pair[1].trim();
String key = pair[0].trim();
switch (key) {
case "kernel":
params.kernel_type = parseKernelType(value);
break;
case "degree":
params.degree = Integer.parseInt(value);
break;
case "gamma":
params.gamma = Double.parseDouble(value);
break;
case "coef0":
params.coef0 = Double.parseDouble(value);
break;
case "C":
params.C = Double.parseDouble(value);
break;
case "nu":
params.nu = Double.parseDouble(value);
break;
case "eps":
params.eps = Double.parseDouble(value);
break;
default:
throw new PrestoException(StandardErrorCode.INVALID_FUNCTION_ARGUMENT.toErrorCode(), format("Unknown parameter %s", pair[0]));
}
}
return params;
}
private static int parseKernelType(String value)
{
switch (value.toLowerCase()) {
case "linear":
return svm_parameter.LINEAR;
case "poly":
return svm_parameter.POLY;
case "rbf":
return svm_parameter.RBF;
case "sigmoid":
return svm_parameter.SIGMOID;
default:
throw new PrestoException(INVALID_FUNCTION_ARGUMENT.toErrorCode(), format("Unknown kernel type %s", value));
}
}
}