title: Python: Pandas Concatenate each row into a string
body: <p>I have the following Pandas Dataframe:</p>
  
  <pre><code>df=pd.DataFrame({0:["a","b","c","d"], 1:["e","f","g",None], 2:["h",None,None,None]})
  
     0     1     2
  0  a     e     h
  1  b     f  None
  2  c     g  None
  3  d  None  None
  </code></pre>
  
  <p>I like to create a new DataFrame with one column where each row is a concatenated string, with a seperator ",":</p>
  
  <pre><code>       0
  0  a,e,h
  1    b,f
  2    c,g
  3      d
  </code></pre>
  
  <p>For a single row I could use </p>
  
  <pre><code>df.iloc[0,:].str.cat(sep=",")
  </code></pre>
  
  <p>but how can I apply this to the whole DataFrame, without using a for-loop (if possible) </p>