how we can convert categorical data in a column into numbered data : <p>Lets take an example, suppose my table values are:</p>

<p><strong>subjects</strong></p>

<p>english </p>

<p>mathematics </p>

<p>science </p>

<p>english </p>

<p>science</p>

<p>how can i convert these string data into numbered data as shown in table below.</p>

<p><strong>subjects</strong></p>

<p>1</p>

<p>2</p>

<p>3</p>

<p>1</p>

<p>3</p>
