I am new to programming and F# is my first .NET language as well as my first functional language. As a beginner's project, I would like to try implementing my own duplicate file finder, and I am looking for some tips on the F# tools that are relevant to my project. I apologise in advance if my question doesn't meet StackOverflow's standards: I will gladly make changes to it as required.
Here is the rough idea I have come up with: I will retrieve all files from a desired folder, read the file contents into byte arrays, and then use a hash-table to store the byte arrays and remove duplicates. Will more experienced programmers tell me whether this is a good approach? What improvements can I make? Additionally, as asked earlier, what are the relevant F# tools to look at? MSDN has a huge list of libraries and namespaces and etc., and it is really overwhelming for a newbie like me.
Thank you warmly in advance for your help!
I'd recommend starting with a console application.
There are a couple of relevant .Net APIs:
System.IO.Directory.GetFiles
System.IO.Directory.EnumerateFiles
GetFiles returns an easy to use array of all file paths but blocks until all files are found, where as EnumerateFiles lets you enumerate the files one-by-one and give feedback to the user.
For performance when finding duplicates, the file length can be used to find potential duplicates before comparing the data. Here you could use the Length property of System.IO.FileInfo.
If you create a sequence of tuple of file name and file length, you could use Seq.groupBy to group potential matches. Finally for groups of 2 or more you can read the files and compare the bytes to find exact duplicates.
Related
I am new to this site and I would like to get some inputs regarding parsing STDF files. Generally speaking, I am trying to parse a STDF file to gather only the results (numbers) and not the rest of the line. If I am able to achieve this, I would then like to compare all the numbers together through a bubble sort or insertion sort and see if any numbers are equal to each other. I am capable of doing this in C/C++ and Java but I have no experience parsing documents using Scripts.
Could anyone push me in the right direction? What should I be reading to learn my way around this?
Are you already using an STDF library?
You did not mention one, so I assume not.
You should find a library you are comfortable with (the list changes over time, but you can find some by Googling or looking at the STDF page on Wikipedia) rather than attempting to parse STDF yourself, unless you have a good reason to recreate the STDF parser wheel.
An STDF file contains many tests. It generally does not make sense to compare the results for different tests, so I assume you are looking for matching values within the set of results for each test.
I would use your chosen STDF parser to read the value of each test for each part. Keep a set of the results for each test. As you read each new result, check the set to see if already exists. If it does, you have found the case you were looking for, otherwise add the result to the set.
I am currently working on my first small desktop menubar app (macOS, Swift 3). It needs to access
a) A list of words (Think word dictionary, 1k-5k words, per supported language)
b) A list of structured data (Think simple structs, ~500)
I am currently pondering, whether to build these in code - maybe a factory class per language. Or include them in my app as json and parse at runtime. Or maybe build an SQLite file and read that during runtime, although that approach would be harder to diff in source control ...
As I am new to the platform I was wondering whether there might be a better way that I am not aware of, or maybe performance considerations that render one of the mentioned approaches useless.
As usual, thanks in advance folks !
Your listed solutions can be used for this task. However I think for such kind of tasks the best solution is to use CoreData, where you can store a list of words as well as structured data, also make relations between them if you need it
I'm hoping somebody out there can help me with this. I'm attempting to extract some barcode data from some .dat files. Its a B Tree file system with groups of three files .dat .ix. .dia. The company that wrote the software (a long time ago) say that the program is written in Pascal. I have no experience in reverse engineering but from what I read its most likely the only way to extract the data as the structure of the database is contained in the code of the program. I'm looking for advice on where to start.
I suppose the first thing you need to do is to see if the exe you've got was written with Delphi. You can check with this: http://cc.embarcadero.com/Item/15250
Then, to see if the exe that creates those .dat files were made with 'TurboPower B-Tree Filer', the I'd suggest you download and take a look at this: http://sourceforge.net/projects/tpbtreefiler/
At this step, looking at these sources is needed to familiarize yourself with the class names used in 'TurboPower B-Tree Filer' to help determine if any of those classes were used in your exe.
Then, using 'XN Resource Editor' [search the Internet for this] or, probhably better, 'MiTeC Portable Executable Reader' [ http://www.mitec.cz/pe.html ], see if any class names are relevant.
If they are, then you're in luck --sort of. All you will need to do is to write an app using 'TurboPower B-Tree Filer' to import the data in your dat files to export or manipulate as you wish.
At that point, you might find this link useful.
TurboPower B-Tree Filer and Delphi XE2 - Anyone done it?
If, OTOH, none of the above applies; I fear the only option is to reverse engineer the exe you have.
I am a novice Go lang programmer,trying to learn Go lang features.I wanted to split a large csv file into multiple files in GO lang, each file containing the header.How do i do this? I have searched everywhere but couldnt get the right solution.Any help in this regard will be greatly appreciated.
Also please suggest me a good book for reference.
Thanking You
Depending on your shell fu this problem might be better suited for common shell utilities but you specifically mentioned go.
Let's think through the problem.
How big is this csv file? Are we talking 100 lines or is it 5G ?
If it's smallish I typically use this:
http://golang.org/pkg/io/ioutil/#ReadFile
However, this package also exists:
http://golang.org/pkg/encoding/csv/
Regardless - let's return to the abstraction of the problem. You have a header (which is the first line) and then the rest of the document.
So what we probably want to do (if ignoring csv for the moment) is to read in our file.
Then we want to split the file body by all the newlines in it.
You can use this to do so:
http://golang.org/pkg/strings/#Split
You didn't mention but do you know how many files you want to split by or would you rather split by the line count or byte count? What's the actual limitation here?
Generally it's not going to be file count but if we pretend it is we simply want to divide our line count by our expected file count to give lines/file.
Now we can take slices of the appropriate size and write the file back out via:
http://golang.org/pkg/io/ioutil/#WriteFile
A trick I use sometime to help think me threw these things is to write down our mission statement.
"I want to split a large csv file into multiple files in go"
Then I start breaking that up into pieces but take the divide/conquer approach - don't try to solve the entire problem in one go - just break it up to where you can think about it.
Also - make gratiutious use of pseudo-code until you can comfortably write the real code itself. Sometimes it helps to just write a short comment inline with how you think the code should flow and then get it down to the smallest portion that you can code and work from there.
By the way - many of the golang.org packages have example links where you can literally run in your browser the example code and cut/paste that to your own local environment.
Also, I know I'll catch some haters with this - but as for books - imo - you are going to learn a lot faster just by trying to get things working rather than reading. Action trumps passivity always. Don't be afraid to fail.
Here is a package that might help. You can set a necessary chunk size in bytes and a file will be split on an appropriate amount of chunks.
Sadly, a project that I have been working on lately has a large amount of copy-and-paste code, even within single files. Are there any tools or techniques that can detect duplication or near-duplication within a single file? I have Beyond Compare 3 and it works well for comparing separate files, but I am at a loss for comparing single files.
Thanks in advance.
Edit:
Thanks for all the great tools! I'll definitely check them out.
This project is an ASP.NET/C# project, but I work with a variety of languages including Java; I'm interested in what tools are best (for any language) to remove duplication.
Check out Atomiq. It finds code that is duplicate that is prime for extracting to one location.
http://www.getatomiq.com/
If you're using Eclipse, you can use the copy paste detector (CPD) https://olex.openlogic.com/packages/cpd.
You don't say what language you are using, which is going to affect what tools you can use.
For Python there is CloneDigger. It also supports Java but I have not tried that. It can find code duplication both with a single file and between files, and gives you the result as a diff-like report in HTML.
See SD CloneDR, a tool for detecting copy-paste-edit code within and across multiple files. It detects exact copyies, copies that have been reformatted, and near-miss copies with different identifiers, literals, and even different seqeunces of statements.
The CloneDR handles many languages, including Java (1.4,1.5,1.6) and C# especially up to C#4.0. You can see sample clone detection reports at the website, also including one for C#.
Resharper does this automagically - it suggests when it thinks code should be extracted into a method, and will do the extraction for you
Check out PMD , once you have configured it (which is tad simple) you can run its copy paste detector to find duplicate code.
One with some Office skills can do following sequence in 1 minute:
use ordinary formatter to unify the code style, preferably without line wrapping
feed the code text into Microsoft Excel as a single column
search and replace all dual spaces with single one and do other replacements
sort column
At this point the keywords for duplicates will be already well detected. But to go further
add comparator formula to 2nd column and counter to 3rd
copy and paste values again, sort and see the most repetitive lines
There is an analysis tool, called Simian, which I haven't yet tried. Supposedly it can be run on any kind of text and point out duplicated items. It can be used via a command line interface.
Another option similar to those above, but with a different tool chain: https://www.npmjs.com/package/jscpd