title: Pandas: replace substring in string
body: <p>I want to replace substring <code>icashier.alipay.com</code> in column in <code>df</code></p>
  
  <pre><code>url
  icashier.alipay.com/catalog/2758186/detail.aspx
  icashier.alipay.com/catalog/2758186/detail.aspx
  icashier.alipay.com/catalog/2758186/detail.aspx
  vk.com
  </code></pre>
  
  <p>to <code>aliexpress.com</code>.</p>
  
  <p>Desire output</p>
  
  <pre><code>aliexpress.com/catalog/2758186/detail.aspx
  aliexpress.com/catalog/2758186/detail.aspx
  aliexpress.com/catalog/2758186/detail.aspx
  vk.com
  </code></pre>
  
  <p>I try <code>df['url'].replace('icashier.alipay.com', 'aliexpress.com', 'inplace=True')</code> but it return <code>empty dataframe</code>.</p>