Python: How to properly call a method? - python-2.7

Question

I have this class:
class Tumor(object):
"""
Wrapper for the tumor data points.
Attributes:
idNum = ID number for the tumor (is unique) (int)
malignant = label for this tumor (either 'M' for malignant
or 'B' for benign) (string)
featureNames = names of all features used in this Tumor
instance (list of strings)
featureVals = values of all features used in this Tumor
instance, same order as featureNames (list of floats)
"""
def __init__(self, idNum, malignant, featureNames, featureVals):
self.idNum = idNum
self.label = malignant
self.featureNames = featureNames
self.featureVals = featureVals
def distance(self, other):
dist = 0.0
for i in range(len(self.featureVals)):
dist += abs(self.featureVals[i] - other.featureVals[i])**2
return dist**0.5
def getLabel(self):
return self.label
def getFeatures(self):
return self.featureVals
def getFeatureNames(self):
return self.featureNames
def __str__(self):
return str(self.idNum) + ', ' + str(self.label) + ', ' \
+ str(self.featureVals)
and I am trying to use an instance of it in another function later in my code:
def train_model(train_set):
"""
Trains a logistic regression model with the given dataset
train_set (list): list of data points of type Tumor
Returns a model of type sklearn.linear_model.LogisticRegression
fit to the training data
"""
tumor = Tumor()
features = tumor.getFeatures()
labels = tumor.getLabel()
log_reg = sklearn.linear_model.LogisticRegression(train_set)
model = log_reg.fit(features, labels)
return model
However, I keep getting this error when I test my code:
TypeError: __init__() takes exactly 5 arguments (1 given)
I understand that I am not using the five arguments when I create the instance of Tumor in train_model , but how can I do so?

Answer 1

Arguments to the __init__ (or __new__, if you're using that) just go, predictably, where you create the instance in train_model:
tumor = Tumor(idNum, malignant, featureNames, featureVals)
Of course, you actually need values for all of these, as they are all required arguments.
You don't need to include self, however, as that first argument is taken care of automatically.