title: Confused with Clustering
body: <p>I am getting so confused with clustering in data science process. 
  We know that the process of grouping similar points in a 2D space is based on this formula:</p>
  
  <pre><code>distance = sqrt( (x2-x1)^2 + (y2-y1)^2 )
  
  </code></pre>
  
  <p>But in introducing inputs to the sklearn we just feed the x-axis values :( what happened to the y-axis values?</p>
  
  <p>for example we have the following data base:</p>
  
  <pre><code>index    x     y
  ------------------
    0      5     8
    1      6     9
    2      7     10
  
  </code></pre>
  
  <p>and we introduce x to the KMeans</p>
  
  <pre><code>from sklearn.cluster import KMeans
  kmeans = KMeans(2)
  kmeans.fit(df["x"])
  </code></pre>
  
  <p>How can it calculate distance without having y values?</p>