K-Means.ipynb

Hello,

when I input values of shape (1000,1), I'm getting a lot of NaNs in the centroid list.

array([[-0.0615779 ],
       [ 0.        ],
       [-0.01855482],
       [        nan],
       [        nan],
       [        nan],
       [        nan],
       [-0.03768255],
       [ 0.01288017],
       [ 0.01535422],
       [ 0.04958867],
       [        nan],
       [-0.01960552],
       [ 0.09472825],
       [-0.09461572],
       [        nan]]

Basically I want to do the same as this MATLAB code does:

  >> load fisheriris
  >> X = meas(:,3); 
  >> [idx,C] = kmeans(X,3);
  >> size(X) => [150,1]
  >> size(idx) => [150,1]
  >> size(C) => [3,1]

I think there's problem with the calculation of means, because this is where the assignment for centroids is coming from, but I'm not sure where the nan is coming from. Can somebody please give me a hint to fix? :)

tf.sub need changes to tf.subtract
and

means = tf.concat(0, [
    tf.reduce_mean(
        tf.gather(vectors,
                  tf.reshape(
                    tf.where(
                      tf.equal(assignments, c)
                    ),[1,-1])
                 ),reduction_indices=[1])
    for c in xrange(num_clusters)])

to

means = tf.concat([
    tf.reduce_mean(
        tf.gather(vectors,
                  tf.reshape(
                    tf.where(
                      tf.equal(assignments, c)
                    ),[1,-1])
                 ),reduction_indices=[1])
    for c in xrange(num_clusters)], 0)

Thank you!!
In python 3 , I think it works!

import matplotlib.pyplot as plt
import numpy as np
import pandas as pd
import seaborn as sns
import tensorflow as tf

num_points = 2000
vectors_set = []

for i in range(num_points):
  if np.random.random() > 0.5:
    vectors_set.append([np.random.normal(0.0, 0.9), np.random.normal(0.0, 0.9)])
  else :
    vectors_set.append([np.random.normal(3.0, 0.5), np.random.normal(1.0, 0.5)])
    
df = pd.DataFrame({"x": [v[0] for v in vectors_set], "y": [v[1] for v in vectors_set]})
sns.lmplot("x","y", data=df, fit_reg=False, size=6)
plt.show()

# k-means algorithm
vectors = tf.constant(vectors_set)
num_clusters = 4
centroides = tf.Variable(tf.slice(tf.random_shuffle(vectors),[0,0],[k,-1]))

expanded_vectors = tf.expand_dims(vectors, 0)
expanded_centroides = tf.expand_dims(centroides, 1)

assignments = tf.argmin(tf.reduce_sum(tf.square(tf.subtract(expanded_vectors,expanded_centroides)), 2), 0)

means = tf.concat(axis=0, values=[
    tf.reduce_mean(
        tf.gather(vectors, 
                  tf.reshape(
                      tf.where(
                          tf.equal(assignments, c)
                      ), [1,-1])
                 ), axis=[1]) 
    for c in range(num_clusters)])

update_centroides = tf.assign(centroides, means)

init_op = tf.initialize_all_variables()

sess = tf.Session()
sess.run(init_op)

for step in range(100):
  _, centroid_values, assignment_values = sess.run([update_centroides, centroides, assignments])
  
data = {"x": [], "y": [], "cluster": []}

for i in range(len(assignment_values)):
  data["x"].append(vectors_set[i][0])
  data["y"].append(vectors_set[i][1])
  data["cluster"].append(assignment_values[i])
  
df = pd.DataFrame(data)
sns.lmplot("x","y",data=df,fit_reg=False, size=6, hue="cluster", legend=False)
plt.show()

In python 3.6, it still works well. Thank You :D

import matplotlib.pyplot as plt
import numpy as np
import pandas as pd
import seaborn as sns
import tensorflow as tf

num_points = 2000
vectors_set = []

for i in range(num_points):
    if np.random.random() > 0.5:
        vectors_set.append([np.random.normal(0.0, 0.9), np.random.normal(0.0, 0.9)])
    else:
        vectors_set.append([np.random.normal(3.0, 0.5), np.random.normal(1.0, 0.5)])

df = pd.DataFrame({"x": [v[0] for v in vectors_set], "y": [v[1] for v in vectors_set]})
sns.lmplot("x", "y", data=df, fit_reg=False, height=6)
plt.show()

# k-means algorithm
vectors = tf.constant(vectors_set)
num_clusters = 4
centroides = tf.Variable(tf.slice(tf.random_shuffle(vectors), [0, 0], [num_clusters, -1]))

expanded_vectors = tf.expand_dims(vectors, 0)
expanded_centroides = tf.expand_dims(centroides, 1)

assignments = tf.argmin(tf.reduce_sum(tf.square(tf.subtract(expanded_vectors, expanded_centroides)), 2), 0)

means = tf.concat(axis=0, values=[
    tf.reduce_mean(
        tf.gather(vectors,
                  tf.reshape(
                      tf.where(
                          tf.equal(assignments, c)
                      ), [1, -1])
                  ), axis=[1])
    for c in range(num_clusters)])

update_centroides = tf.assign(centroides, means)

init_op = tf.global_variables_initializer()

sess = tf.Session()
sess.run(init_op)

for step in range(100):
    _, centroid_values, assignment_values = sess.run([update_centroides, centroides, assignments])

data = {"x": [], "y": [], "cluster": []}

for i in range(len(assignment_values)):
    data["x"].append(vectors_set[i][0])
    data["y"].append(vectors_set[i][1])
    data["cluster"].append(assignment_values[i])

df = pd.DataFrame(data)
sns.lmplot("x", "y", data=df, fit_reg=False, height=6, hue="cluster", legend=False)
plt.show()