title: How to resample data in a single dataframe within 3 distinct groups
body: <p>I've got a dataframe and want to resample certain columns (as hourly sums and means from 10-minutely data) WITHIN the 3 different 'users' that exist in the dataset.</p>
  
  <p>A normal resample would use code like:</p>
  
  <pre><code>import pandas as pd
  import numpy as np    
  
  df = pd.read_csv('example.csv')
  
  df['Datetime'] = pd.to_datetime(df['date_datetime/_source'] + ' ' + df['time']) #create datetime stamp
  df.set_index(df['Datetime'], inplace = True)
  
  df = df.resample('1H', how={'energy_kwh': np.sum, 'average_w': np.mean, 'norm_average_kw/kw': np.mean, 'temperature_degc': np.mean, 'voltage_v': np.mean})
  df
  </code></pre>
  
  <p>To geta a result like (please forgive the column formatting, I have no idea how to paste this properly to make it look nice):</p>
  
  <pre><code>                   energy_kwh norm_average_kw/kw    voltage_v   temperature_degc    average_w
  Datetime                    
  2013-04-30 06:00:00  0.027   0.007333    266.333333  4.366667    30.000000
  2013-04-30 07:00:00  1.250   0.052333    298.666667  5.300000    192.500000
  2013-04-30 08:00:00  5.287   0.121417    302.333333  7.516667    444.000000
  2013-04-30 09:00:00  12.449  0.201000    297.500000  9.683333    726.000000
  2013-04-30 10:00:00  26.101  0.396417    288.166667  11.150000   1450.000000
  2013-04-30 11:00:00  45.396  0.460250    282.333333  12.183333   1672.500000
  2013-04-30 12:00:00  64.731  0.440833    276.166667  13.550000   1541.000000
  2013-04-30 13:00:00  87.095  0.562750    284.833333  13.733333   2084.500000
  </code></pre>
  
  <p>However, in the original CSV, there is a column containing URLs - in the dataset of 100,000 rows, there are 3 different URLs (effectively IDs).  I want to have each resampled individually rather than having a 'lump' resample from all (e.g. 9.00 AM on 2014-01-01 would have data for all 3 users, but each should have it's own hourly sums and means).</p>
  
  <p>I hope this makes sense - please let me know if I need to clarify anything.</p>
  
  <p>FYI, I tried using the advice in the following 2 posts but to no avail:</p>
  
  <p><a href="https://stackoverflow.com/questions/15617496/resampling-a-multi-index-dataframe">Resampling a multi-index DataFrame</a></p>
  
  <p><a href="https://stackoverflow.com/questions/15799162/resampling-within-a-pandas-multiindex">Resampling Within a Pandas MultiIndex</a></p>
  
  <p>Thanks in advance</p>