Source code for coremltools.converters.libsvm._libsvm_converter

# Copyright (c) 2017, Apple Inc. All rights reserved.
# Use of this source code is governed by a BSD-3-clause license that can be
# found in the LICENSE.txt file or at

from coremltools import __version__ as ct_version
from coremltools.models import _METADATA_SOURCE, _METADATA_VERSION

from ..._deps import _HAS_LIBSVM

def _infer_min_num_features(model):
    # find the largest index of all the support vectors
    max_index = 0
    for i in range(model.l):
        j = 0
        while model.SV[i][j].index != -1:
            cur_last_index = model.SV[i][j].index
            j += 1
        if cur_last_index > max_index:
            max_index = cur_last_index
    return max_index

[docs]def convert(libsvm_model, feature_names, target, input_length, probability): """ Convert a support vector machine (SVM) model to the protobuf spec. Supports: * C-SVC * nu-SVC * Epsilon-SVR * nu-SVR Parameters ---------- model_path: libsvm_model Libsvm representation of the model. feature_names : [str] | str Names of each of the features. target: str Name of the predicted class column. probability: str Name of the class probability column. Only used for C-SVC and nu-SVC. Returns ------- model_spec: An object of type Model_pb. Protobuf representation of the model """ if not (_HAS_LIBSVM): raise RuntimeError("libsvm not found. libsvm conversion API is disabled.") from libsvm import svm as _svm from ...models import MLModel from ...proto import Model_pb2 svm_type_enum = libsvm_model.param.svm_type # Create the spec export_spec = Model_pb2.Model() export_spec.specificationVersion = SPECIFICATION_VERSION if svm_type_enum == _svm.EPSILON_SVR or svm_type_enum == _svm.NU_SVR: svm = export_spec.supportVectorRegressor else: svm = export_spec.supportVectorClassifier # Set the features names inferred_length = _infer_min_num_features(libsvm_model) if isinstance(feature_names, str): # input will be a single array if input_length == "auto": print( "[WARNING] Inferring an input length of %d. If this is not correct," " use the 'input_length' parameter." % inferred_length ) input_length = inferred_length elif inferred_length > input_length: raise ValueError( "An input length of %d was given, but the model requires an" " input of at least %d." % (input_length, inferred_length) ) input = export_spec.description.input.add() = feature_names input.type.multiArrayType.shape.append(input_length) input.type.multiArrayType.dataType = Model_pb2.ArrayFeatureType.DOUBLE else: # input will be a series of doubles if inferred_length > len(feature_names): raise ValueError( "%d feature names were given, but the model requires at" " least %d features." % (len(feature_names), inferred_length) ) for cur_input_name in feature_names: input = export_spec.description.input.add() = cur_input_name input.type.doubleType.MergeFromString(b"") # Set target output = export_spec.description.output.add() = target # Set the interface types if svm_type_enum == _svm.EPSILON_SVR or svm_type_enum == _svm.NU_SVR: export_spec.description.predictedFeatureName = target output.type.doubleType.MergeFromString(b"") nr_class = 2 elif svm_type_enum == _svm.C_SVC or svm_type_enum == _svm.NU_SVC: export_spec.description.predictedFeatureName = target output.type.int64Type.MergeFromString(b"") nr_class = len(libsvm_model.get_labels()) for i in range(nr_class): svm.numberOfSupportVectorsPerClass.append(libsvm_model.nSV[i]) svm.int64ClassLabels.vector.append(libsvm_model.label[i]) if probability and bool(libsvm_model.probA): output = export_spec.description.output.add() = probability output.type.dictionaryType.MergeFromString(b"") output.type.dictionaryType.int64KeyType.MergeFromString(b"") export_spec.description.predictedProbabilitiesName = probability else: raise ValueError( "Only the following SVM types are supported: C_SVC, NU_SVC, EPSILON_SVR, NU_SVR" ) if libsvm_model.param.kernel_type == _svm.LINEAR: svm.kernel.linearKernel.MergeFromString( b"" ) # Hack to set kernel to an empty type elif libsvm_model.param.kernel_type == _svm.RBF: svm.kernel.rbfKernel.gamma = libsvm_model.param.gamma elif libsvm_model.param.kernel_type == _svm.POLY: = svm.kernel.polyKernel.c = libsvm_model.param.coef0 svm.kernel.polyKernel.gamma = libsvm_model.param.gamma elif libsvm_model.param.kernel_type == _svm.SIGMOID: svm.kernel.sigmoidKernel.c = libsvm_model.param.coef0 svm.kernel.sigmoidKernel.gamma = libsvm_model.param.gamma else: raise ValueError( "Unsupported kernel. The following kernel are supported: linear, RBF, polynomial and sigmoid." ) # set rho # also set probA/ProbB only for SVC if svm_type_enum == _svm.C_SVC or svm_type_enum == _svm.NU_SVC: num_class_pairs = nr_class * (nr_class - 1) // 2 for i in range(num_class_pairs): svm.rho.append(libsvm_model.rho[i]) if bool(libsvm_model.probA) and bool(libsvm_model.probB): for i in range(num_class_pairs): svm.probA.append(libsvm_model.probA[i]) svm.probB.append(libsvm_model.probB[i]) else: svm.rho = libsvm_model.rho[0] # set coefficients if svm_type_enum == _svm.C_SVC or svm_type_enum == _svm.NU_SVC: for _ in range(nr_class - 1): svm.coefficients.add() for i in range(libsvm_model.l): for j in range(nr_class - 1): svm.coefficients[j].alpha.append(libsvm_model.sv_coef[j][i]) else: for i in range(libsvm_model.l): svm.coefficients.alpha.append(libsvm_model.sv_coef[0][i]) # set support vectors for i in range(libsvm_model.l): j = 0 cur_support_vector = svm.sparseSupportVectors.vectors.add() while libsvm_model.SV[i][j].index != -1: cur_node = cur_support_vector.nodes.add() cur_node.index = libsvm_model.SV[i][j].index cur_node.value = libsvm_model.SV[i][j].value j += 1 model = MLModel(export_spec) from libsvm import __version__ as libsvm_version libsvm_version = "libsvm=={0}".format(libsvm_version) model.user_defined_metadata[_METADATA_VERSION] = ct_version model.user_defined_metadata[_METADATA_SOURCE] = libsvm_version return model