title: How to predict values of column in new Python data frame using info from the old data frame
body: <p>Let's assume I have two data frames df1 and df2. In df1 I have several columns such as userid, sexid, location and etc. And in df2 I have all the same columns as in df1 except for sexid which I need to fill using some prediction algorithm. 
  I am just a beginner and I tried another kind of problems. So any advice or useful references which may help me to crack it are welcomed.</p>