[R] XML: Reading transition matrices into R

[stefan.duke at gmail.com]

Hello,
thanks a lot. This is a form which I can work with in R.

Another question, which I hope is not a bridge too far: Can I write
the R matrix which your code created back into the xml format (i.e.
with the same tags and structure) from which it came and hence feed it
back to the original software?

Best,
Stefan


On Thu, Nov 12, 2009 at 3:17 PM, Duncan Temple Lang
<duncan at wald.ucdavis.edu> wrote:
>
>
> stefan.duke at gmail.com wrote:
>> Hello,
>> from a software I have the following output in xml (see below):
>> It is a series of matrices, for each age one. I have 3 categories
>> (might vary in the application), hence, 3x3 matrices where each
>> element gives the probability of transition from i to j. I would like
>> read this data into R (preferably in a list, where each list element
>> is one of the age specific matrices) and - after altering the values
>> in R - write it back into the file.  I know that there is an xml
>> package in R with which I have already struggled, but I have to admit
>> my understanding is too limited. Maybe somebody had a similar problem
>> or know the code of the top of his or her head.
>
> Hi Stefan
>
>  There are many approaches for handling this. I assume that the primary
> obstacle you are facing is extracting the values from the XML.  The following
> will do that for you.
> We start with the content in transition.xml (or in a string in R).
> Since the XML is very shallow, i.e. not very hierarchical, and all
> the information is in the transition nodes under the root, we can
> use xmlToList().
> This returns a list with an element for each <transition>
> element, and such elements are character vectors containing the
> values from age, sex, from, to, and percent.
> So I've put these into a matrix and you are now back entirely
> within R and can group the values by age and arrange them into
> the individual transition matrices.
>
>
>   doc = xmlParse("transition.xml")
>   matrix(as.numeric(unlist(xmlToList(doc))), , 5, byrow = TRUE,
>          dimnames = list(NULL, names(xmlRoot(doc)[[1]])))
>
>
>  D.
>
>
>
>>
>> Any help appreciated.
>>
>> Thanks and best,
>> Stefan
>>
>>
>>
>>
>>
>> <?xml version="1.0" encoding="UTF-8" standalone="no"?><transitionmatrix>
>> <transition><age>0</age><sex>0</sex><from>1</from><to>1</to><percent>99.99999</percent></transition><transition><age>0</age><sex>0</sex><from>1</from><to>2</to><percent>0.0</percent></transition><transition><age>0</age><sex>0</sex><from>1</from><to>3</to><percent>0.0</percent></transition><transition><age>0</age><sex>0</sex><from>2</from><to>1</to><percent>0.0</percent></transition><transition><age>0</age><sex>0</sex><from>2</from><to>2</to><percent>99.999985</percent></transition><transition><age>0</age><sex>0</sex><from>2</from><to>3</to><percent>0.0</percent></transition><transition><age>0</age><sex>0</sex><from>3</from><to>1</to><percent>0.0</percent></transition><transition><age>0</age><sex>0</sex><from>3</from><to>2</to><percent>0.0</percent></transition><transition><age>0</age><sex>0</sex><from>3</from><to>3</to><percent>99.999985</percent></transition><transition><age>0</age><sex>1</sex><from>1</from><to>1</to><percent>100.0</percent></transition><transition><age>0<
> /!
>>  age><sex>1</sex><from>1</from><to>2</to><percent>0.0</percent></transition><transition><age>0</age><sex>1</sex><from>1</from><to>3</to><percent>0.0</percent></transition><transition><age>0</age><sex>1</sex><from>2</from><to>1</to><percent>0.0</percent></transition><transition><age>0</age><sex>1</sex><from>2</from><to>2</to><percent>100.0</percent></transition><transition><age>0</age><sex>1</sex><from>2</from><to>3</to><percent>0.0</percent></transition><transition><age>0</age><sex>1</sex><from>3</from><to>1</to><percent>0.0</percent></transition><transition><age>0</age><sex>1</sex><from>3</from><to>2</to><percent>0.0</percent></transition><transition><age>0</age><sex>1</sex><from>3</from><to>3</to><percent>100.0</percent></transition><transition><age>1</age><sex>0</sex><from>1</from><to>1</to><percent>99.99999</percent></transition><transition><age>1</age><sex>0</sex><from>1</from><to>2</to><percent>0.0</percent></transition><transition><age>1</age><sex>0</sex><from>1</fro
> m!
>>  ><to>3</to><percent>0.0</percent></transition><transition><age>1</age>
>> <sex>0</sex><from>2</from><to>1</to><percent>0.0</percent></transition><transition><age>1</age><sex>0</sex><from>2</from><to>2</to><percent>99.999985</percent></transition><transition><age>1</age><sex>0</sex><from>2</from><to>3</to><percent>0.0</percent></transition><transition><age>1</age><sex>0</sex><from>3</from><to>1</to><percent>0.0</percent></transition><transition><age>1</age><sex>0</sex><from>3</from><to>2</to><percent>0.0</percent></transition><transition><age>1</age><sex>0</sex><from>3</from><to>3</to><percent>99.999985</percent></transition><transition><age>1</age><sex>1</sex><from>1</from><to>1</to><percent>100.0</percent></transition><transition><age>1</age><sex>1</sex><from>1</from><to>2</to><percent>0.0</percent></transition><transition><age>1</age><sex>1</sex><from>1</from><to>3</to><percent>0.0</percent></transition><transition><age>1</age><sex>1</sex><from>2</from><to>1</to><percent>0.0</percent></transition><transition><age>1</age><sex>1</sex><from>2</fro
> m!
>>  ><to>2</to><percent>100.0</percent></transition><transition><age>1</age><sex>1</sex><from>2</from><to>3</to><percent>0.0</percent></transition><transition><age>1</age><sex>1</sex><from>3</from><to>1</to><percent>0.0</percent></transition><transition><age>1</age><sex>1</sex><from>3</from><to>2</to><percent>0.0</percent></transition><transition><age>1</age><sex>1</sex><from>3</from><to>3</to><percent>100.0</percent></transition><transition><age>2</age><sex>0</sex><from>1</from><to>1</to><percent>99.35205</percent></transition><transition><age>2</age><sex>0</sex><from>1</from><to>2</to><percent>0.6479474</percent></transition><transition><age>2</age><sex>0</sex><from>1</from><to>3</to><percent>0.0</percent></transition><transition><age>2</age><sex>0</sex><from>2</from><to>1</to><percent>0.0</percent></transition><transition><age>2</age><sex>0</sex><from>2</from><to>2</to><percent>97.101456</percent></transition><transition><age>2</age><sex>0</sex><from>2</from><to>3</to><perc
> e!
>>  nt>2.8985496</percent></transition><transition><age>2</age><sex>0</sex
>>> <from>3</from><to>1</to><percent>0.0</percent></transition><transition><age>2</age><sex>0</sex><from>3</from><to>2</to><percent>0.0</percent></transition><transition><age>2</age><sex>0</sex><from>3</from><to>3</to><percent>100.0</percent></transition><transition><age>2</age><sex>1</sex><from>1</from><to>1</to><percent>97.82136</percent></transition><transition><age>2</age><sex>1</sex><from>1</from><to>2</to><percent>2.1786473</percent></transition><transition><age>2</age><sex>1</sex><from>1</from><to>3</to><percent>0.0</percent></transition><transition><age>2</age><sex>1</sex><from>2</from><to>1</to><percent>0.0</percent></transition><transition><age>2</age><sex>1</sex><from>2</from><to>2</to><percent>93.33336</percent></transition><transition><age>2</age><sex>1</sex><from>2</from><to>3</to><percent>6.6666408</percent></transition><transition><age>2</age><sex>1</sex><from>3</from><to>1</to><percent>0.0</percent></transition><transition><age>2</age><sex>1</sex><from>3</from
>>!
>>  <to>2</to><percent>0.0</percent></transition><transition><age>2</age><sex>1</sex><from>3</from><to>3</to><percent>100.0</percent></transition>
>> </transitionmatrix>
>>
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