gaCommonInitializationSteps

Description

functions that initialize the global environment for GA-scripts.

'gaCommonInitializationSteps' uses the content of the GA definition file to add some necessary variables to the global environment. these include for example 'inputFileName', 'outputFileName', the names of the input and output columns, the logging object.

'blendInGlobals' does a similar thing with the extra configuration file. it reads the /root/globals/NAME elements and puts their textual value into the corresponding NAME global variable. if a 'type' attribute is present, the character value is converted as the specified type.

Usage

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gaCommonInitializationSteps(gaDefFile, gaExtraConfFile, testCase)
blendInGlobals(xmldoc, envir, element, ...)

Arguments

gaDefFile

character: the name of the file defining the general adapter. it's optional and if missing, the first command line argument will be used.

gaExtraConfFile

character: the name of the file containing extra configuration items, that do not fit in the general adapter definition file. it's optional, defaults to the second command line argument or is simply skipped.

testCase

character: use this parameter only for testing. if given, the function will put this name just in front of the input file as retrieved from the GA file.

xmldoc

XmlDoc: the object containing the extra configuration.

envir

environment: the target environment where to export globals, defaults to the '.GlobalEnv'.

element

character: if not specified, the globals are assumed to be common to all scripts and we look for them under /root/globals. use 'element' to override this. you can use XPath syntax and pass extra parameters in the '...' optional arguments.

...

further specifies the element that contains the globals.

Details

the easiest way to use the function 'gaCommonInitializationSteps' is by invoking it, without arguments, as the first action in an R script.

for testing, debugging and interactive usage, you would invoke it with explicit arguments.

invoked without arguments, 'gaCommonInitializationSteps' will use the first two arguments on the command line which run the script.

the first argument is interpreted as the location of the xml that defines the general adapter.

the information read is then placed in the global environment so your script can access it easily. the names of the parameters being exported are hard coded and closely mimics the names of the xml elements containing the values, with the important difference that we look at the data from the receiving end. the objects exported by FEWS are input to our script and what FEWS hopes to import is for our script the output. this difference is reflected in the names of the globals.

if there's a second argument, 'gaCommonInitializationSteps' will use it to initialize an XmlDoc object and store it globally as 'extraConf'. no assumption is made on the structure of this xml file, except that it must be parseable.

apart from data extracted from the FEWS GA configuration file, 'gaCommonInitializationSteps' defines the global variable 'gaConfDir' as the name of the directory directly containing the FEWS GA configuration file. The rationale behind this is that you can use it to select (using XPath) elements in a common extraConf object.

Examples

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## Not run: gaCommonInitializationSteps() ## gets arguments from command line 
## Not run: gaCommonInitializationSteps("ga_conf.xml", "metadata.xml")