Remote access using python

The easiest way to use the Madrigal python remote data access API is to simply let the web interface write the script you need for you. Just choose the Access data pull-down menu and choose Create a command to download multiple exps. Then follow the instructions, and you will have the command you need to download whatever you want from Madrigal. Be sure to select python as the language you want to create the command with. You can choose to download files as they are in Madrigal in either column-delimited ascii, Hdf5, or netCDF4 formats, or you can choose the parameters yourself (including derived parameters), and optionally include filters on the data you get back.

This web interface will generate python commands using one of the following two Python scripts: globalDownload.py and globalIsprint.py. Use globalDownload.py if you want data as it is in Madrigal. Use globalIsprint.py to choose parameters and/or filters. These two scripts are documented below, for those who do not want to use the web interface to generate the needed arguments:

Finally, this page describes the script globalCitation.py. This script is used to create a permanent citation to a group of Madrigal files.

globalDownload.py

globalIsprint.py

globalCitation.py

The script globalCitation.py runs a global search through Madrigal data, and returns a permanent citation to the group of files.

The rest of this tutorial is for those who want to go beyond the automatically generated commands and write more advanced python applications that access Madrigal data.

This page describes the remote Python API, and gives some examples of using this API. These examples have been tested on both Windows and Linux, and require only access to the internet and python 2.3 to run. It is available for download here.

The remote Python API is organized in the same way as the Madrigal data model, from Instrument at the highest level, down to the level of data values. Readers who are not familiar with the Madrigal data model should read the material in that section before proceeding with this tutorial.

The basic object in the remote Python API is the MadrigalData, found in the madrigalWeb module. To initialize MadrigalData requires only the url of the home page on any Madrigal 2.3 (or above) site as an argument. Calling the methods of this object will return all possible information from one Madrigal site. The other objects in madrigalWeb are simply there to hold returned information - for example, the MadrigalExperiment object holds information about one experiment.

Two applications written with the remote Python API follow. The first is a simple regression test that is run to test web services when Madrigal is installed. The second is a script that downloads realtime data from any desired Madrigal site.

This example also shows how to get data from a different Madrigal site than the one you start with.

To use this regression test, cd to the examples directory in the installation directory, and type:

"""exampleMadrigalWebServices.py runs an example of the Madrigal Web Services interface
   for a given Madrigal server.

   usage:

   python exampleMadrigalWebServices.py 

"""

# $Id: exampleMadrigalWebServices.py 3984 2012-03-20 14:20:17Z brideout $

import madrigalWeb.madrigalWeb

# constants
user_fullname = 'Bill Rideout - automated test'
user_email = 'brideout@haystack.mit.edu'
user_affiliation = 'MIT Haystack'

madrigalUrl = 'http://madrigal.haystack.mit.edu'


testData = madrigalWeb.madrigalWeb.MadrigalData(madrigalUrl)



print 'Example of call to getAllInstruments'
instList = testData.getAllInstruments()
# print out Millstone
for inst in instList:
    if inst.code == 30:
        print (str(inst) + '\n')
        

print 'Example of call to getExperiments'
expList = testData.getExperiments(30, 1998,1,19,0,0,0,1998,1,22,0,0,0)
for exp in expList:
    # should be only one
    print (str(exp) + '\n')


print 'Example of call to getExperimentFiles'
fileList = testData.getExperimentFiles(expList[0].id)
for thisFile in fileList:
    if thisFile.category == 1:
        print (str(thisFile.name) + '\n')
        thisFilename = thisFile.name
        break
    
print 'Example of downloadFile - simple and hdf5 formats:'
result = testData.downloadFile(thisFilename, "/tmp/test.txt", 
                               user_fullname, user_email, user_affiliation, "simple")
result = testData.downloadFile(thisFilename, "/tmp/test.hdf5", 
                               user_fullname, user_email, user_affiliation, "simple")

print 'Example of simplePrint - only first 1000 characters printed'
result = testData.simplePrint(thisFilename, user_fullname, user_email, user_affiliation)
print result[:1000]
print

print 'Example of call to getExperimentFileParameters - only first 10 printed'
fileParms = testData.getExperimentFileParameters(thisFilename)
for i in range(10):
    print fileParms[i]
print


print 'Example of call to isprint (prints data)'
print(testData.isprint(thisFilename,
                       'gdalt,ti',
                       'filter=gdalt,500,600 filter=ti,1900,2000',
                       user_fullname, user_email, user_affiliation))


print 'Example of call to madCalculator (gets derived data at any time)'
result = testData.madCalculator(1999,2,15,12,30,0,45,55,5,-170,-150,10,200,200,0,'sdwht,kp')
for line in result:
    for value in line:
        print ('%8.2e ' % (value))
    print('\n')

print 'Example of searching all Madrigal sites for an experiment - here we search for PFISR data'
expList = testData.getExperiments(61,2008,4,1,0,0,0,2008,4,30,0,0,0,local=0)
print expList[0]

print 'Since this experiment is not local (note the experiment id = -1), we need to create a new MadrigalData object to get it'
testData2 = madrigalWeb.madrigalWeb.MadrigalData(expList[0].madrigalUrl)

print 'Now repeat the same calls as above to get PFISR data from the SRI site'
expList2 = testData2.getExperiments(61,2008,4,1,0,0,0,2008,4,30,0,0,0,local=1)
print 'This is a PFISR experiment'
print expList2[0]

The following is a demonstration script that shows how real-time data can be imported from any Madrigal site that is updated on a real-time basis.

In this example, data is imported from http://www.haystack.mit.edu/madrigal from "Millstone Hill IS Radar". The following Madrigal parameters are retrieved:

Although the particular Madrigal site (http://www.haystack.mit.edu/madrigal), the instrument ("Millstone Hill IS Radar"), the parameters, and the times are hard-coded in this example, they could be easily be modified to be arguments.

To avoid missing data, we choose one parameter to be the filter parameter: vo. By filtering on this parameter, any "missing" values are filtered out.

To run this script requires the python Madrigal API be installed, which can be downloaded from http://www.haystack.edu/madrigal/madDownload.html.