title: How to make particular column values as upper case?
body: <p>If I have a dataframe like</p>
  <pre><code>a     b     c
  
  bob   ram   sam
  john  hp    hcl
  </code></pre>
  <p>Now how do I make a and b column values as uppercase</p>
  <p>For single column</p>
  <pre><code>df['a'] = df['a'].str.upper()
  </code></pre>
  <p>For all columns</p>
  <pre><code>df = df.applymap(lambda s:s.upper() if type(s) == str else s)
  </code></pre>
  <p>or</p>
  <pre><code>df.apply(lambda x: x.str.lower() if(x.dtype == 'object') else x)
  </code></pre>
  <p>Expected output</p>
  <pre><code>a     b  
  
  BOB   RAM
  JOHN  HP  
  </code></pre>
  <p>How do we do it for two columns at once? Like we could do the single column one twice but looking for how to do for both columns.</p>