import datetime
import pandas as pd
import numpy as np

dates = pd.date_range(datetime.datetime(2012, 4, 5, 11,
0),datetime.datetime(2012, 4, 7, 7, 0),freq='5H')

var1 = np.random.sample(dates.size) * 10.0
var2 = np.random.sample(dates.size) * 10.0
df = pd.DataFrame(data={'var1': var1, 'var2': var2}, index=dates)

df1=df.resample('D').mean()

count
3
5
7

df1=df.resample('D').agg(['mean','count'])
print (df1)
                var1            var2
                mean count      mean count
2012-04-05  3.992166     3  4.968410     3
2012-04-06  6.843105     5  6.193568     5
2012-04-07  4.568436     1  3.135089     1