title: Convert complex strings to real numbers
body: <p>After doing some calculation, I ended up with a data frame full of such values <code>'(312+0j)'</code>. Complex numbers but strings. How can I convert them back to real numbers? I have no complex numbers at all, due to some calculations in <code>np.eignval</code> it add the <code>+0j</code>. I am thinking of doing a regex but wanted to know if there is a faster and easier way to accomplish this.</p>