double distance_between_variable_vectors(const VariableVector& vec1, const VariableVector& vec2) {
// Both vectors must have the same dimension
if (vec1.size() != vec2.size()) {
return -1;
}
double square_distance = 0;
string var_name;
double val1, val2;
for (VariableVector::const_iterator it = vec1.begin(); it != vec1.end(); ++it) {
var_name = it->first;
// Both vectors must have exactly the same variables
if (vec2.count(var_name) == 0) {
return -1;
}
val1 = vec1.at(var_name);
val2 = vec2.at(var_name);
square_distance += pow((val1 - val2), 2);
}
return pow(square_distance, 0.5);
}
VariableVector increment_weight_vector(const VariableVector& weights, const VariableVector& scaled_gradient) {
VariableVector empty;
if (weights.size() != scaled_gradient.size()) {
return empty;
}
VariableVector incremented;
string partial_name, weight_name;
double scaled_partial, weight_val;
for (VariableVector::const_iterator it = scaled_gradient.begin(); it != scaled_gradient.end(); ++it) {
partial_name = it->first;
scaled_partial = it->second;
weight_name = partial_name_to_weight_name(partial_name);
if (weights.count(weight_name) == 0) {
return empty;
}
weight_val = weights.at(weight_name);
incremented.insert(make_pair(weight_name, weight_val + scaled_partial));
}
return incremented;
}
VariableVector add_variable_vectors(const VariableVector& vec1, const VariableVector& vec2) {
VariableVector empty;
VariableVector sum;
string var_name;
double component_sum;
// if the vectors are of different sizes, return empty
if (vec1.size() != vec2.size()) return empty;
for (VariableVector::const_iterator it1 = vec1.begin(); it1 != vec1.end(); ++it1) {
var_name = it1->first;
// if this variable is in both vectors, add the values
if (vec2.count(var_name) != 0) {
component_sum = it1->second + vec2.at(var_name);
sum.insert(make_pair(var_name, component_sum));
}
// if this variable is only in vec1, return empty
else {
return empty;
}
}
// if we reach this point, every variable in vec1 is also in vec2
// since both vectors are of the same size, it is safe to return
return sum;
}