How to use pyomo to load *.sol file - pyomo

I use pyomo to write the script, but use external solver to do the optimization.
The external solver return a *.sol file. My question is that if pyomo or any package of python can decode the sol file, and pass the decision variable result into the original model. Therefore, we can do some post analysis.

I wanted to add this as a comment but I dont have enough reputation.
I was facing a similar problem with CPLEX. See this question. You have to basically store the variable map and use it while parsing the solution file. In my case CPLEX gives solution in XML format, so I used XML parser.
Hope this helps!

Related

How are QR codes generated in Qt-C++ and how do can I store one as an image to place it in a pdf file generated?

I want to generate a QR code to encrypt data I am entering what's the easiest way for that to be implemented? I can't seem to find anything in the documentation to suggest any classes that can handle this. There seem to be external libraries but I don't know how to include them. So what steps should I take to solve my problem?

How to parse the java comments of a groovy file to html format?

I have a set of .groovy files (Java). All of these files have the same comment format.
I developped a tool with wich I'm able to read those files and applying a REGEX to get all the comments in a list. (Finally i just have to copy paste these comments to .html file)
I would like to know if it's a correct practice in order to generate a HTML page with the comment (a kind of documentation). If not, what would you recommend ?
I read about Doxygen and Javadoc but i'm not sure about using them (if they can be really useful in my case since the comments are already written)
If you can suggest a library in order to generate easily a HTML Webpage or any other advice.
Any help is appreciated.
There exists Groovydoc which is roughly the equivalent of Javadoc, just for Groovy.
As your setup is not that (you already have comments, probably not in Groovydoc format, and you have half the tooling), there are still multiple ways open to you. As you already extract the documentation from groovy, if I were you, I would do a minimal post-formatting, if necessary, and output the documentation as markdown (e.g., github markdown) or asciidoc (e.g., asciidoctor). Then you can use any preferred tool to convert the post-formatted documentation into HTML.
To answer the question "How to parse the java comments" – you shouldn't. If possible, especially in a new project, stick with the standard tooling. In the case of Groovy that's Groovydoc. The normal (non Java/Groovy-Doc style) comments themselves you should never need to extract from the source code. They should be so much context-specific, that without the corresponding code they are anyways useless.

Implementing Data Frames in OCaml

I have been learning OCaml on my own and I've been really impressed with the language. I wanted to develop a small machine learning library for practice but I've been presented with a problem.
In Python one can use Pandas to load data files then pass it to a library like Scikit-Learn very easily. I would like to emulate the same process in OCaml. However, there doesn't seem to be any data frames library in OCaml. I've checked 'ocaml-csv' but it doesn't really seem to be doing what I want. I also looked into 'Frames' from Haskell but it uses TemplateHaskell but I believe a simpler way to do the same thing should be possible if Pandas can simply load the data file into memory without compile-time metaprogramming.
Does anyone know how data frames are implemented in Pandas or R, a quick search on Google doesn't seem to return useful links.
Is it possible to use a parser generator such as Menhir to parse CSV files? Also, I'm unsure how static typing works with data frames.
Would you have a reference about the format of data frames? It may not be so hard to add to ocaml-csv if CSV is the underlying representation. The better is to open an issue with a request and the needed information.

Cross Validation in libsvm

I'm using libsvm library in my project and have recently discovered that it provides out-of-the-box cross validation.
I'm checking the documentation and it says clearly that I have to call svm-train with -n switch to use CV feature
.
When I call it with -v switch I cannot get a model file which is needed by svm-predict.
Implementing Support Vector Machine from scratch is beyond the scope of my project, so I'd rather fix this one if it is broken or ask the community for support.
Can anybody help with that?
Here's the link to the library, implemented in C and C++, and here is the paper that describes how to use it.
Cause libsvm use cv only for parameter selection.
From libsvm FAQ:
Q: After doing cross validation, why there is no model file outputted ?
Cross validation is used for selecting good parameters. After finding them, you want to re-train the whole data without the -v option.
If you are going to use cv for estimating quality of classifier on your data you should implement external cross validation by splitting data, train on some part and test on other.
It's been a while since I used libsvm so I don't think I have the answer you're looking, but if you run the cross-validation and are satisfied with the results, running lib-svm with the same parameters without the -v will yield the same model.

building objects from xml file at runtime and initializing, in one pass?

I have to parse the XML file and build objects representation based on that, now once I get all these data I create entries in various database for these data objects. I have to do second pass over that for value as in the first pass all I could do is build the assets in various databases. and in second pass I get the values for all the data and put it in the database.
I have a feeling that this can be done in a single pass but I just want to see what are your opinions. As I am just a student who started with professional work, experienced ppl please help.
Can someone who have ideas or done similar work, please provide some light on the topic so that I can think over the possibility of the work and get the prototype going based on your suggestion.
Thanks a lot for your precious time, I honestly appreciate it.
You might be interested in learning several techniques of building XML parsers like DOM or SAX. As it is said in SAX description the only thing which requires second pass could be the XML validation but not the creating the tree.
Beside DOM and SAX parsing, you can use XQuery for querying data from XML files.It is fast, robust and efficient.
here is a link
You can use Qt Xml module for DOM ,SAX and XQuery, btw it is open source.
Another option is xml - C++ data binding, Here is the link.You can create C++ codes from definition directly.It is an elegant solution.
EDIT:
the latter one is at compile time.
You can also use Apache Licensed http://xmlbeansxx.touk.pl/. It works under Windows and Linux.
you could take a look at the somewhat simpler 'pull' api called stax instead of using sax (event based).