title: Python pandas, converting multiple columns of strings into time?
body: <p>I have a pandas DataFrame which consists of many columns which are strings represented as times (e.g. "8:14:30.123"). Is there an efficient way of converting all of these columns into numerical values? I did some research and found panda <code>to_datetime()</code> function, but it works only for one column at a time, and I have too many columns to iterate over.</p>