title: Problem using string conditional with np.select
body: <p>I'm trying to create a new column in a pandas dataframe based on whether a string is contained in another column. I'm using np.select based on this <a href="https://stackoverflow.com/questions/19913659/pandas-conditional-creation-of-a-series-dataframe-column">post</a>. Here is an example dataframe and an example function to create the new column</p>
  
  <pre class="lang-py prettyprint-override"><code>df=pd.DataFrame({'column':['one','ones','other','two','twos','others','three','threes']})
  
  def add(df):
  
      conditions = [
          ('one' in df['column']),
          ('two' in df['column']),
          ('three' in df['column']),
          ('other' in df['column'])] 
  
      choices = [1, 2, 3, 0]
      df['Int'] = np.select(conditions, choices, default=0)
  
      return df
  
  new_df=add(df)
  </code></pre>
  
  <p>The output I'm getting is</p>
  
  <pre class="lang-py prettyprint-override"><code>   column  Int
  0     one    0
  1    ones    0
  2   other    0
  3     two    0
  4    twos    0
  5  others    0
  6   three    0
  7  threes    0
  </code></pre>
  
  <p>And what I want is</p>
  
  <pre class="lang-py prettyprint-override"><code>   column  Int
  0     one    1
  1    ones    1
  2   other    0
  3     two    2
  4    twos    2
  5  others    0
  6   three    3
  7  threes    3
  </code></pre>
  
  <p>what am I doing wrong?</p>