mean calculation in pandas excluding zeros

It also depends on the meaning of 0 in your data.

• If these are indeed ‘0’ values, then your approach is good

• If ‘0’ is a placeholder for a value that was not measured (i.e. ‘NaN’), then it might make more sense to replace all ‘0’ occurrences
  with ‘NaN’ first. Calculation of the mean then by default exclude NaN
  values.

  df = pd.DataFrame([1, 0, 2, 3, 0], columns=['a'])
  df = df.replace(0, np.NaN)
  df.mean()