Python unkown operand type - for custom class

I have a custom class in my Python code, that handles k-means clustering. The class takes some arguments to customize the clustering, however when subtracting two values from a list passed to the class, I get the following error:

Traceback (most recent call last):
File "/home/dev/PycharmProjects/KMeans/KMeansApplication.py", line 22, in <module>
application()
File "/home/dev/PycharmProjects/KMeans/KMeansApplication.py", line 16, in application
opt_num_clusters = cluster_calculator.calculate_optimum_clusters()
File "/home/dev/PycharmProjects/KMeans/ClusterCalculator.py", line 19, in calculate_optimum_clusters
self.init_opt_line()
File "/home/dev/PycharmProjects/KMeans/ClusterCalculator.py", line 33, in init_opt_line
self. m = (self.sum_squared_dist[0] - self.sum_squared_dist[1]) / (1 - self.calc_border)
TypeError: unsupported operand type(s) for -: 'KMeans' and 'KMeans'


Here is the code of my custom class:

import KMeansClusterer
from math import sqrt, fabs
from matplotlib import pyplot as plp

class ClusterCalculator:
m = 0
b = 0
sum_squared_dist =
derivates =
distances =
line_coordinates =

def __init__(self, calc_border, data):
self.calc_border = calc_border
self.data = data

def calculate_optimum_clusters(self):
self.calculate_squared_dist()
self.init_opt_line()
self.calc_distances()
self.calc_line_coordinates()
opt_clusters = self.get_optimum_clusters()
print("Evaluated", opt_clusters, "as optimum number of clusters")
return opt_clusters


def calculate_squared_dist(self):
for k in range(1, self.calc_border):
kmeans = KMeansClusterer.KMeansClusterer(k, self.data)
self.sum_squared_dist.append(kmeans.calc_custom_params(self.data, k))

def init_opt_line(self):
#here the error is thrown
self. m = (self.sum_squared_dist[0] - self.sum_squared_dist[1]) / (1 - self.calc_border)
self.b = (1 * self.sum_squared_dist[0] - self.calc_border*self.sum_squared_dist[0]) / (1 - self.calc_border)

def calc_y_value(self, x_calc):
return self.m * x_calc + self.b

def calc_line_coordinates(self):
for i in range(1, self.calc_border):
self.line_coordinates.append(self.calc_y_value(i))

def calc_distances(self):
for i in range(1, self.calc_border):
self.distances.append(sqrt(fabs(self.calc_y_value(i))))
print("For border", self.calc_border, ", calculated the following distances: n", self.distances)

def get_optimum_clusters(self):
return self.distances.index((max(self.distances)))

def plot_results(self):
plp.plot(range(1, self.calc_border), self.sum_squared_dist, "bx-")
plp.plot(range(1, self.calc_border), self.line_coordinates, "bx-")
plp.xlabel("Number of clusters")
plp.ylabel("Sum of squared distances")
plp.show()


I append the KMeansClusterer as well, because sum_squared_dist is filled with values of there:

sum_squared_dist

from sklearn.cluster import KMeans
from matplotlib import pyplot as plp
class KMeansClusterer:
def __init__(self, clusters, data):
self.clusters = clusters
self.data = data

def cluster(self):
kmeans = KMeans(n_clusters=self.cluster(), random_state=0).fit(self.data)
print("Clustered", len(kmeans.labels_), "GTINs")
for i, cluster_center in enumerate(kmeans.cluster_centers_):
plp.plot(cluster_center, label="Center 0".format(i))
plp.legend(loc="best")
plp.show()

def calc_custom_params(self, data_frame, clusters):
kmeans = KMeans(n_clusters=clusters, random_state=0).fit(data_frame)
return kmeans

def cluster_without_plot(self):
return KMeans(n_clusters=self.cluster(), random_state=0).fit(self.data)


I cannot imagine why '-' should be unsupported, i trie to subtract two list values of type integer and 1 and a integer variable.

Can someone help me?

2 Answers
2

KMeans.fit() returns a class instance, which implies calc_custom_params() returns a class instance, so your list sum_squared_dist does not contain integers, the elements are objects of the sklearn.cluster.KMeans class.

KMeans.fit()

calc_custom_params()

sum_squared_dist

sklearn.cluster.KMeans

Python cannot automatically subtract classes. You need to implement the __sub__ method on your class for python to know how to handle subtracting these classes. You can find the full reference here https://docs.python.org/3/library/operator.html

__sub__

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