add a new column based on values from other column using a function pandas python
<p>I have a dataframe and I want to add a new column based on some processing on an existing column.</p>

<pre><code>import pandas as pd
def func_processcol(l):
     processedl=l+1
     return processedl
df = pd.DataFrame({'a':['l1','l2','l3','l4','l5','l6'],
                       'b':['1','2','2','1','2','2']})
</code></pre>

<p>Now I want to add a new column to dataframe by passing the values in column a .
df[e]=[l1+1, ....]</p>