Getting started with Mathematica packages - wolfram-mathematica

Can someone offer some advice on how to get started with mathematica packages?
I can save the following in a file named "Foo.m". When I run the input cell in that file, I can see the effects reflected in $ContextPath variable.
BeginPackage["Foo`"]
bar::usage = "barfunction";
Begin["`private`"]
bar[w_] := w;
End[];
EndPackage[];
However, in my notebook I have the following:
#include<foo>
SetDirectory[ToFileName[{$HomeDirectory, "My Documents", "mathematica"}]];
Needs["Foo`"]
$ContextPath
But the needs call is failing for some reason, and the $ContextPath remains unchanged.
Edit
I believe that I've got a partial solution working now, the cell in my file wasn't marked as an initialization cell - and whilst I can now <<Foo', Needs["Foo"]` still isn't working correctly.

Check to make sure the saved file, "Foo.m", is on your $Path, which tells Mathematica which directories to look in when trying to load packages, much like the PATH environment variable in Unix or Windows.
EDIT: $ContextPath won't be changed unless there's an actual BeginPackage statement (or you manipulate it directly using Set or Block or something).
EDIT the second: One thing to check is what
FileNames["Foo.m", $Path]
returns. What you're describing does sound a little strange, though.

Either form should work. When a file is loaded using Get (or <<) or Needs, the directory on the top of the DirectoryStack[] is searched first, and then the $Path is searched. (SetDirectory does not change $Path, so FileNames["Foo.m", $Path]won't find Foo.m.) However, FindFile by default searches Directory[] and $Path. You can test it by doing the following:
FindFile["Foo`"]
SetDirectory[<Foo dir>]
FindFile["Foo`"]
it should return
$Failed
<Foo dir>
<Foo dir>/foo.m
If FindFile can find Foo.m then Needs should be able to find it. In general, I put my packages in $UserBaseDirectory/Applications, and Needs picks them up just fine.

Related

Command Prompt: Move a file to an Unknownly named folder

So, is there a possible way to move Test.txt to C:\ProgramData\CsD2\Tools\("Unknown Folder Name")\data\per Using command prompt?
using foxidrives solution for your previous question for detecting the correct directory, then just
move test.txt "%folder%\"
Short answer: yes. Not quite sure what the situation is that has left only the middle part of your path unknown, and the need to use the comnand line, but I have encountered similar cases on Linux and expect the algoirthm can be adapted to Windows commands. It's possible to do this by hand rather than writing a shell script, but it's up to you and your skills.
Permissions matter. Make sure you elevate yours enough to read and write in Tools before continuing.
First, change directory to C:\ProgramData\CsD2\Tools\
Presumably there are many items here. Some may be "hidden," so list the contents of this directory and be sure to include an option to show hidden files and folders. If you can, restrict the search to directories only.
It's tempting to display contents recursively in the above step. It's up to you, but I find it makes the output cluttered without a script to do the rest of the work.
Now it's time to search for the subfolder set that theoretically only exists in your target folder. Suppose Tools contains the directories fldr1, fldr2, and fldr3. Use your command to list a directory's contents with the path "fldr1\data\per", then use "fldr2\data\per", and so on until it doesn't return an error. Per may be empty, but that should look different from the path not found error.
Now you've found the name of your mystery folder. Write it down for future reference.
At thus point, you know the path to Test.txt, and the full path to the destination directory. Do a move command to relocate Test.txt, and you're done. I like to relist the contents of the target directory after to be comfortable that it arrived.

Rstudio difference between run and source

I am using Rstudio and not sure how options "run" and "source" are different.
I tried googling these terms but 'source' is a very common word and wasn't able to get good search results :(
Run and source have subtly different meanings. According to the RStudio documentation,
The difference between running lines from a selection and invoking
Source is that when running a selection all lines are inserted
directly into the console whereas for Source the file is saved to a
temporary location and then sourced into the console from there
(thereby creating less clutter in the console).
Something to be aware of, is that sourcing functions in files makes them available for scripts to use. What does this mean? Imagine you are trying to troubleshoot a function that is called from a script. You need to source the file containing the function, to make the changes available in the function be used when that line in the script is then run.
A further aspect of this is that you can source functions from your scripts. I use this code to automatically source all of the functions in a directory, which makes it easy to run a long script with a single run:
# source our functions
code.dir <- "c:\temp"
code.files = dir(code.dir, pattern = "[.r]")
for (file in code.files){
source(file = file.path(code.dir,file))
}
Sometimes, for reasons I don't understand, you will get different behavior depending on whether you select all the lines of code and press the run the button or go to code menu and chose 'source.' For example, in one specific case, writing a gplot to a png file worked when I selected all my lines of code but the write failed to when I went to the code menu and chose 'source.' However, if I choose 'Source with Echo,' I'm able to print to a png file again.
I'm simply reporting a difference here that I've seen between the selecting and running all your lines and code and going to code menu and choosing 'source,' at least in the case when trying to print a gplot to a png file.
An important implication of #AndyClifton's answer is:
Rstudio breakpoints work in source (Ctrl-Shift-S) but not in run (Ctrl-Enter)
Presumably the reason is that with run, the code is getting passed straight into the console with no support for a partial submission.
You can still use browser() though with run though.
print() to console is supported in debugSource (Ctrl-Shift-S) as well as run.
The "run" button simply executes the selected line or lines. The "source" button will execute the entire active document. But why not just try them and see the difference?
I also just discovered that the encoding used to read the function sourced can also be different if you source the file or if you add the function of the source file to your environment with Ctrl+Enter!
In my case there was a regex with a special character (ยต) in my function. When I imported the function directly (Ctrl+Enter) everything would work, while I had an error when sourcing the file containing this function.
To solve this issue I specified the encoding of the sourced file in the source function (source("utils.R", encoding = "UTF-8")).
Run will run each line of code, which means that it hits enter at the beginning of each line, which prints the output to the console. Source won't print anything unless you source with echo, which means that ggplot won't print to pngs, as another posted mentioned.
A big practical difference between run and source is that if you get an unaccounted for error in source it'll break you out of the code without finishing, whereas run will just pass the next line to the console and keep going. This has been the main practical difference I've seen working on cleaning up other people's scripts.
When using RSTudio u can press the run button in the script section - it will run the selected line.
Next to it you have the re - run button, to run the line again. and the source button next to it will run entire chuncks of code.
I found a video about this topic:
http://www.youtube.com/watch?v=5YmcEYTSN7k
Source/Source with echo is used to execute the whole file whereas Run as far as my personal experience goes executes the line in which your cursor is present.
Thus, Run helps you to debug your code. Watch out for the environment. It will display what's happening in the stack.
To those saying plots do not show. They won't show in Plots console. But you can definitely save the plot to disc using Source in RStudio. Using this snippet:
png(filename)
print(p)
dev.off()
I can confirm plots are written to disc. Furthermore print statements are also outputted to the console

How to browse for file (Win7/64bits)

I need to quickly write a simple GUI over a command line application. Two steps are required:
Specify an input file path,
Specify an output file path (non existing)
I found out a previous post, however trying to get the above (1) to work seems like an insane task.
Indeed BrowseForFolder seems to only work in some weird cases, you can use BIF_BROWSEINCLUDEFILES for only *.pdf and/or *.txt (trial and errors). I can get an error if I select a *.dll and/or a *.jpg (don't ask).
So instead, I gave up this approach and followed another one, in this case (objIE.Document.all.FileSelect), only the name of the selected file is returned the path seems to be always set to "c:/fakepath" for some reason. So again I am missing the full path to be able to pass that to the command line app.
Is there any sane way (<10 lines of codes) to get (1) and (2) working on Win7/64bits (VBS, HTA...)?
Don't know if people are still interested in the BrowseForFolder file selection issue, but here's what I've found.
I had the same issue selecting files with BrowseForFolder using &H4000 / BIF_BROWSEINCLUDEFILES. I could get a return with .docx but not .doc files and as you say .pdf files.
For me .txt wouldn't return anything, as didn't WMI Backup .rec files that I needed for a script I'm writing, resulting in this error information:-
Error: Unspecified error
Code: 80004005
Source: (null)
After looking at other solutions I came back to this one as my preferred choice, plus it was doing my head in that it didn't want to work. So at the bitter end it seems to be this easy.
To get my .rec files recognized I add this to the registry:-
[HKEY_CLASSES_ROOT\.rec]
#="WMI.Backup"
[HKEY_CLASSES_ROOT\WMI.Backup]
#="WMI Backup"
"BrowseInPlace"="1"
To get .txt files recognized I add this to the registry:-
[HKEY_CLASSES_ROOT\txtfile]
"BrowseInPlace"="1"
So "BrowseInPlace"="1" seems to be the nugget.
Seems so unbelievably easy that I'm sure this solution is out there somewhere but I never came across it so thought I'd put it online.
I would be interested to find that it works for others as I fear that this issue may of sent me mad, still can't believe it seems to work.
Hope this helps.
Here are 3 different ways to do what you want:
http://www.robvanderwoude.com/vbstech_ui_fileopen.php

Relative paths for portable notebooks in mathematica

I Cannot find how to use relative paths in mathematica. My directory structure is simple.
Import["G:\\Research\\Acc and Vel Runs\\5-24\\Mathematica\\Data\\250 \
Acc.xls"][[1]] // TableForm
That Demonstrates the Absolute path by using the insert path from the menus. I want this notebook to be portable. I want to give someone the "Mathematica" directory and I want them to be able to run the code. I don't want the paths to break because It will be run on a different machine. Basically I just want to use a relative path starting at the Mathematica level shown above.
In Mathematica you can get the current directory using Directory[] and you can set it to something else using SetDirectory[]. You can go back to the last location using ReserDirectory[] or check all previous locations using DirectoryStack[].
This is described in the documentation here.
You can set the current directory to the directory where the notebook is using
SetDirectory[NotebookDirectory[]]
For NotebookDirectory to work, you must be using the Front End and the notebook must be saved.
You can always use path relative to the current directory (Directory[]), for example Import["data/somedata.txt"].
Regarding directory separators: / will always works, on all of Windows/Linux/Mac. When you are typing a relative path name, it's much more convenient to just use / for portability than FileNameJoin.
I usually do this.
SetDirectory[
FileNameJoin[{$InitialDirectory, "dir1", "dir2"}]];
Quiet[Close["Log.txt"]];
logStream = Quiet[OpenWrite["xmlAreaTagsLog.txt"]];
xmlDoc = Import["XmlData.xml"];
Using $InitialDirectory gets you the .nb directory and using FileNameJoin allows you to have relative access.

Ruby - How to prevent wiping your hard drive when using delete file and directory commands in your code

I'm writing some code that at run time may create or delete directories within the project path. I haven't really used ruby for file processing so i'm really uneasy about having code that, with a few mistypes weeks down the line, could result in wiping other directories outside of my project path.
Is there anyway to make it impossible for the program to delete files outside of its own path regardless of whats typed in destructive calls?
Pathname is a wrapper class for almost any file operations.
require "pathname"
path= Pathname.new("/home/johannes")
path.directory? # => true
path.children # => [#<Pathname:.bash_history>, #<Pathname:Documents>, #<Pathname:Desktop>]
path.children.each do |p|
p.delete if p.file?
end
Pathname#children does not contain . or .. so you don't accidently walk up the tree instead of down. If you still don't trust in the code, you can even check if on path is contained in another
Pathname.new("test") <=> Pathname.new("test/123") # => -1
You might want to create a wrapper method around your favourite delete method (or, perhaps, around whole class, because not only deleting files is potentially destructive file operation), which would expand all the submitted paths and check whether they begin with your "sandbox" path). You can also try to redefine delete method, if you are willing to cripple it through whole application.
And maybe the cleanest solution of them all would be to create a new user on your system and run your program as him.
On a POSIX system, you can use Dir.chroot to change the root that your application sees. Then ALL actions, not just delete ones, will be limited to the project directory. This does mean that external commands will be unavailable unless you make them part of your project directory as well.
This is the standard 'sandboxing' method used in Unix based systems. It can be difficult to setup (eliminating all external dependancies is sometimes hard), but affords significant protection when configured properly.
You could generate an Array of filenames in your project directory using
my_files = Dir["/bla/bla/your/directory/**/*"]
and then simply check if the filename passed to your "delete" function exist in your my_files array.
I'm sure there is a more elegant solution, but this could work ^_^
You could use File.expand_path and File.dirname on the input, and check that against __FILE__. So something like this might work:
File.delete(path) if File.dirname(File.expand_path(path)).include? File.dirname(File.expand_path(__FILE__))
I've got automated tests that routinely create and wipe out directories. I've taken two approaches:
Use /tmp as much as possible. The 'tmpdir' standard library module will create temporary directories which will be destroyed when your program exits. Or,
When the code creates a directory that it will later be deleting, it drops a marker file into the directory. When it comes time to delete the directory, if the marker file is not found, the code refuses to delete the directory. A marker file might be called ".ok_to_delete", for example.

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