I've been using something like the following with some success:
#!/usr/bin/env python
from __future__ import division
import os,sys
import re
import time
import math
import Globals
from Products.ZenUtils.ZenScriptBase import ZenScriptBase
# device name in Zenoss
devicename = "localhost"
# stand-in for metrics
metric = 'laLoadInt5'
# polling interval in seconds
interval = 300
# sample period in seconds
period = 86400
# first determine current time in epoch
now = int(time.time())
# subtract 24 hours from current time in epoch
yesterday = now - period
samples = int(period/interval)
# array to hold today's data
todaysData=[]
# find the device
dmd = ZenScriptBase(connect=True).dmd
devices = dmd.Devices.getSubDevices()
for device in devices:
print device.id
if str(device.id) == devicename:
print "found",device.id
rrdsource = device
# for each interval in the day, pull the RRD data
alpha = yesterday
while samples > 0 :
omega = alpha + interval
value = rrdsource.getRRDValue(metric, start=alpha, end=omega, function="LAST")
todaysData.append(value)
alpha = yesterday + interval
samples = samples - 1
print "samples:",len(todaysData)
for data in todaysData:
print data
