Processing without entirely loading a table [closed] - r

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I have a file of approximately 40Gb and i need to perform some analytics activity on it but my ram is limited to 4gb any suggestions how to proceed?

Check out the LaF package. It allows you to do column selection and filtering on files that would not otherwise fit into memory.
Documentation and examples are a little thin on the ground which is a shame given that the syntax is a little idiosyncratic. This may help:
https://stackoverflow.com/a/24716798/1427069

Increase Your Virtual Memory:
increase the size of the paging file

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When is it appropriate to use metamodels instead of an expensive analysis? [closed]

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When should one consider using a metamodel in place of an expensive analysis component? I haven't actually seen an example of an openMDAO project that uses metamodels yet, so I was wondering if they're recommended or whether it's still best to treat expensive analyses like normal ones.
Using a metamodel is a trade-off. You trade accuracy vs execution time so it is up to you in your context.

Writing R-thonic code in R [closed]

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What were the design decisions that led to R having often more than one way of doing things, that have subtle difference? See, for a good example,
https://www.r-bloggers.com/r-na-vs-null/
More more such issues are here, some which are justified, some which are not http://r4stats.com/articles/why-r-is-hard-to-learn/
From a software engineering perspective, having such choices in a language screams for having subtle and hard-to-find bugs in your code (e.g. in Python the whole point of writing "pythonic" code, that avoids ambiguity and is easy to read and consistent in style). So there must be some major advantages of having that. What are they?

Detect a TrueCrypt Volume [closed]

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I think I set up a TrueCrypt volume on my Win7 machine a few months ago. Now I cannot remember where I set it up or what the password might be. Is there any way that I can detect this volume? I would have maybe gave it a capacity of 2GB or thereabouts so I don't want that storage going to waste.
If I uninstall TrueCrypt, would that release the volume assigned to it?
GF
Try a disk utility that allows you to locate large files or sort files by size (such as windirstat, although there are many others). A file that's 2GB should stand out.
Search your disk for a file with extension tc (*.tc).
There is no volume assigned unless you assign one (a drive letter). So you can uninstall freely.

What is profiling in unix? [closed]

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Can anybody tell me about 'profiling' in unix by giving a small example.
Thank you!
You'll need to give us some more context if you want a useful answer. Broadly speaking, profiling a program is to instrument the executable with some extra statements that record details of execution which you can later analyse to identify parts that are slow, consume too much memory, consume too much CPU etc. Here's a quickie along with examples on how to use gprof which is the GNU profiler for C. http://www.cs.utah.edu/dept/old/texinfo/as/gprof.html#SEC2
If you want to shine in your exam about profiling, talk about Dtrace.

What is 'System Usage Specification'? [closed]

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My software is a video-audio converter and video cutter. I have used Qt(compiled from source) and ffmpeg (compiled from source). I have to prepare System Usage Specification outline and Specify Usage patterns of the system and indicate it using Run charts / Histograms. I am told to use Winrunner for this purpose. I don't know exactly what to do. Please help.
I never heard about 'System Usage Specification', this must be a terminology specific to your company.
A wild guess would be that it's something close to the Use Case diagram of UML, to define what the users can do and which action they have to perform to lead them to the expected result.
Sounds like a uggly word for "handbook" or "usage guide" from the pov of a end-user (though I never heared of that specific term)

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