PyRRD An Object-Oriented Python Interface for RRDTool
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PyRRD Tags

Python library Python interface Python interface RRDTool object-oriented interface

PyRRD Description

An Object-Oriented Python Interface for RRDTool PyRRD is an object-oriented wrapper for the command line graphing and round-robin database utility, rrdtool. It originally had two design goals:1. provide an interface to rrdtool that Python programmers would love, and2. not depend upon the Python bindings for rrdtool.The reasons for the former are obvious. The motivation for the latter were the many people who had difficulty compiling the rrdtool bindings on their operating system of choice.The PyRRD project has plans of incorporating the Python bindings for those that have them on their system so that they may enjoy both the speed benefits from the bindings as well as the API usability from PyRRD.DependenciesSome parts of PyRRD make use of ElementTree for XML processing. If you have Python 2.5 or greater, PyRRD will use xml.etree. If your Python version is less than 2.5 and you want to use features that depend on XML processing (such as dump function and the fetch/info methods), you will need to install the ElementTree library .InstallationPyRRD is installed in the usual way:python setup.py installYou may also use PyRRD without installing it as long as you have ./ in your PYTHONPATH and you are in the top-level directory (which has the pyrrd child directory).UsageCreate an RRD file programmatically:>>> from pyrrd.rrd import DataSource, RRA, RRD>>> filename = '/tmp/test.rrd'>>> dataSources = []>>> roundRobinArchives = []>>> dataSource = DataSource(... dsName='speed', dsType='COUNTER', heartbeat=600)>>> dataSources.append(dataSource)>>> roundRobinArchives.append(RRA(cf='AVERAGE', xff=0.5, steps=1, rows=24))>>> roundRobinArchives.append(RRA(cf='AVERAGE', xff=0.5, steps=6, rows=10))>>> myRRD = RRD(filename, ds=dataSources, rra=roundRobinArchives,... start=920804400)>>> myRRD.create()Let's check to see that the file exists:>>> import os>>> os.path.isfile(filename)TrueIn order to save writes to disk, PyRRD buffers values and then writes the values to the RRD file at one go:>>> myRRD.bufferValue('920805600', '12363')>>> myRRD.bufferValue('920805900', '12363')>>> myRRD.bufferValue('920806200', '12373')>>> myRRD.bufferValue('920806500', '12383')>>> myRRD.update()Let's add some more data:>>> myRRD.bufferValue('920806800', '12393')>>> myRRD.bufferValue('920807100', '12399')>>> myRRD.bufferValue('920807400', '12405')>>> myRRD.bufferValue('920807700', '12411')>>> myRRD.bufferValue('920808000', '12415')>>> myRRD.bufferValue('920808300', '12420')>>> myRRD.bufferValue('920808600', '12422')>>> myRRD.bufferValue('920808900', '12423')>>> myRRD.update()If you're curious, you can take a look at your rrd file with the following:myRRD.info()The output of that isn't printed here, 'cause it take up too much space. However, it is very similar to the output of the similarly named rrdtool command.In order to create a graph, we'll need some data definitions. We'll also throw in some calculated definitions and variable definitions for good meansure:>>> from pyrrd.graph import DEF, CDEF, VDEF, LINE, AREA, GPRINT>>> def1 = DEF(rrdfile=myRRD.filename, vname='myspeed',... dsName=dataSource.name)>>> cdef1 = CDEF(vname='kmh', rpn='%s,3600,*' % def1.vname)>>> cdef2 = CDEF(vname='fast', rpn='kmh,100,GT,kmh,0,IF')>>> cdef3 = CDEF(vname='good', rpn='kmh,100,GT,0,kmh,IF')>>> vdef1 = VDEF(vname='mymax', rpn='%s,MAXIMUM' % def1.vname)>>> vdef2 = VDEF(vname='myavg', rpn='%s,AVERAGE' % def1.vname)>>> line1 = LINE(value=100, color='#990000', legend='Maximum Allowed')>>> area1 = AREA(defObj=cdef3, color='#006600', legend='Good Speed')>>> area2 = AREA(defObj=cdef2, color='#CC6633', legend='Too Fast')>>> line2 = LINE(defObj=vdef2, color='#000099', legend='My Average',... stack=True)>>> gprint1 = GPRINT(vdef2, '%6.2lf kph')Color is the spice of life. Let's spice it up a little:>>> from pyrrd.graph import ColorAttributes>>> ca = ColorAttributes()>>> ca.back = '#333333'>>> ca.canvas = '#333333'>>> ca.shadea = '#000000'>>> ca.shadeb = '#111111'>>> ca.mgrid = '#CCCCCC'>>> ca.axis = '#FFFFFF'>>> ca.frame = '#AAAAAA'>>> ca.font = '#FFFFFF'>>> ca.arrow = '#FFFFFF'Now we can create a graph for the data in our RRD file:>>> from pyrrd.graph import Graph>>> graphfile = "/tmp/rrdgraph.png">>> g = Graph(graphfile, start=920805000, end=920810000,... vertical_label='km/h', color=ca)>>> g.data.extend()>>> g.write()Let's make sure it's there:>>> os.path.isfile(graphfile)TrueOpen that up in your favorite image browser and confirm that the appropriate RRD graph is generated.Let's clean up the files we've put in the temp directory:>>> os.unlink(filename)>>> os.unlink(graphfile) Requirements: · Python What's New in This Release: · Packaging improvements and loads of documentation.

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