I run Julia on Windows with the julia.bat file given in the zip archive. I have a couple of basic questions. This launches a DOS console.
When typing a plot() command Julia returns plot not defined. How to use the plot() function ? Is there a graphical interface available ?
When typing help I get:
What does it mean ?
There is also the launch-julia-webserver.bat file in the zip archive. When running this file two DOS windows open but nothing else happens. What can we do with this file and how ?
By the way I do not find any documentation answering such basic questions... of course if you know where to find such a documentation it would be an ideal answer.
To answer your immediate question, help is implemented as a function, and functions must be called with parentheses. Try help(), or to get help for a particular function in the standard library supply it as an argument; i.e., help(help).
When you enter a function name without the parentheses, the default is to print all of the implementations with their argument types.
The main Julia documentation is available online at http://docs.julialang.org/. We also have a mailing list at https://groups.google.com/forum/#!forum/julia-dev.
The webserver is pretty rough, especially on Windows. You should be able to open up http://localhost:2000/ with it running and access a web-based command environment. But you'll probably just want to stick to the normal command line.
Another contributor highlighted the response to help as a potential issue for new users and we've opened a bug on it at https://github.com/JuliaLang/julia/issues/1320. It's a new language and there's still plenty of rough edges, so thanks for helping us file those down!
To use launch-julia-webserver.bat, after you double-click it and the two DOS windows open, one of them should say "Connect to http://localhost:2000/ for the web REPL". If you open a web browser to http://localhost:2000/, you should be greeted with a welcome page that asks for your name and a session name.
Related
I am on Windows 10. I want to write a function (in R) to copy the files stored in a camera (actually in the SD of the camera, but I cannot just read the memory card in the PC), to a different storage unit (say, the pc or an external HDD).
The camera is connected to the PC via an USB cable.
The problem I am facing is that, when opening the File Explorer, the camera is showing up as a link under "This PC" with no letter to indicate the drive (e.g., 'G:/').
While I can see the files using the file explorer window, I cannot find a way to get to those file from a cli type of interface (e.g., the command prompt, or the R console).
Googling, I found that 'This PC' is not a folder but rather a link to something in the registry called CLSID for which the identifier should be {20D04FE0-3AEA-1069-A2D8-08002B30309D}. However this is very confusing to me and I cannot figure out how to use this information.
Is there a way to do it? And if so: how?
Please consider I do not know much of commands from prompt (way better off in R).
A CLSID is just a GUID. My computer is a implementation of IShellFolder.
My Computer is part of the shell namespace. Several entries in the shell namespace are virtual (Control panel, scheduled tasks etc.) and cannot be accessed with low-level file functions nor cmd.exe.
While it would be possible to develop a tool that does something like shellcopy Computer\MyCamera\*.jpg x:\backup, I'm not aware of any existing tools that do this. You might have to code it yourself.
In the old days you would call SHGetDesktopFolder to get the root and then use the returned IShellFolder to navigate but these days it is simpler to use IShellItem instead.
To do this it is crucial to understand how IShellFolder and PIDLs work. See Introduction to the Shell Namespace for more information...
In linux machines, it is possible to access where a symbolic link is pointing to by using Sys.readlink function in R or readlink from the command line. Reading its documentation, we see that this is not intended for Windows shortcuts.
In Windows I have not been able to find a one liner to give me where the file points to. The closest I got was from this SO question that demonstrates the use of dir. While the output was not perfect I figured with some regex magic I could isolate the file path.
However when I tried system2('dir'), I received the error "dir" not found.
Is there (a better) way for me to access the file path of a Windows shortcut from R and why can't I use dir through a system call in R?
For anyone in the future finding this thread, the answer is fs::link_path() as pointed out by Edward Visel
I usually open the R console all day long, but sometimes I need to clean my history and my workspace's background so that I can test functions or load new data.
I'm wondering whether there is an easier way to use a command line in .Rprofile so that I can refresh the R console without quitting or rebooting my current session.
What I have usually done for this is to q() without saving and then start R again and clean the History. I think somebody here might be able to give me some better suggestions.
Thanks in advance.
For what concerns history, in UNIX-like systems (mine is Debian) this command refreshes it
loadhistory("")
However, as said in comments, loadhistory seems to be platform-dependent.
Check your ?loadhistory if present on your platform. Mine says:
There are several history mechanisms available for the different
R consoles, which work in similar but not identical ways. There
are separate versions of this help file for Unix and Windows.
The functions described here work on Unix-alikes under the
readline command-line interface but may not otherwise (for
example, in batch use or in an embedded application)
Is there a way in R to enter passwords interactively to the command line and hide them from the screen? I know there's readLine, but I do not know passwords can be hidden there.
Assume you want to connect to a database using ROracle or RMySQL and do not want to store the password in a script but rather make the user enter it every time a query is executed.
Yes, we had a similar question around here, but I feel that the situation has changed and it's worth to address to problem again. Unfortunately tcltk won't work on RStudio (Server).
However I have seen the folks at R Studio found a solution for their version control support. I remember previous versions where I could see my repo password every time I enter it in R Studio, but now that seems to be fixed. I know it's likely R Studio technique, but is there a way mortal R users can access it when working with R Studio Server?
Actually R Studio (Server) provides a nice solution. You can access it by using .rs functions. They provide an undocumented password function which is really nice though there's no guaranteed support forever and a day:
.rs.askForPassword("foo")
You can find the the original hint from RStudio's Josh here:
http://support.rstudio.org/help/discussions/questions/1448-password-interaction-with-dbs-on-rstudio-server
EDIT:
As of 2015 there is another nice solution to enter password interactively. You could use shiny to have a little web based window with a password form. This discussion I had with #hadley shows an example snippet: https://github.com/rstats-db/RPostgres/issues/26
EDIT:
As of 2017 there is another update to this. #m-dz pointed us to this:
rstudioapi::askForPassword("Enter your pw") as well as getPass::getPass() from the R Studio Support webpage. Plus, I also realized that there is .rs.api.askForPassword() which is equivalent to the initially suggested call - at least as far as I've seen.
First off, I will acknowledge that I am aware of another similar thread on the topic of wkhtmltopdf, but it was not similar enough to resolve my issue. Here's the other thread: wkhtmltopdf
Second, I will say that I have successfully used wkhtmltopdf with a Drupal site on a dedicated server that I run, where I installed the libX11 and used the most recent static version of wkhtmltopdf. That's on a CentOS 5 system and it runs nicely.
So, I have another hosting arrangement and I need to get the wkhtmltopdf to work, because it does the most amazing job producing bookmarked PDFs. The PDFs are beautiful.
The hosting is cPanel. I determined that it is on a server that has CentOS 5.5. It is not a problem to drop the static wkhtmltopdf in the print module's lib folder. However, I get the following message back in the Drupal admin status reports page (admin/reports/status).
It says,
"wkhtmltopdf library
The currently selected version of wkhtmltopdf () is not supported. Please update to a newer version."
I have obtained all of the needed .so files for CentOS 5, based on what jockie provided in his answer in the other StackOverflow thread.
Can someone knowledgeable confirm that his list was complete?
The idea of a shell script wrapper seems interesting and appears could be done for Drupal, if the naming of the shell script is called something like "wkhtmltopdf-wrapper.sh".
I have tried to use the shell script code that jockie provided, in a shell script. I did place all of the .so files in a sub-folder called "lib". I confess that I do not know what such things mean, in the script:
export HOME="$PWD"
Can someone interpret for me, what $PWD means?
export LD_LIBRARY_PATH="$PWD/lib/"
I understand that the script is going to get the .so files with that line, yes?
And can someone interpret the following line:
exec $# 2>/dev/null
What I am wondering is, where does the actual pdf get output? I did run the script. It did not throw any errors. However, I did not see a resulting PDF file.
Also, jockie's directions are not totally clear or defined enough. He says, "(some of them are symlinks)" under the list of .so files. Are such lines (in his list), the symlinks?:
lib/libX11.so.6 lib/libX11.so.6.2.0
Or am I mistaken? I was able to get all of them, so I don't know why they would be symlinks. The only thing is, that some of the versions are different. Do I need to delete the following files and make symlinks instead?:
lib/libX11.so.6
lib/libXau.so.6
lib/libxcb.so.1
lib/libXext.so.6
Should the shell script code be written differently, with Drupal in mind?
Thanks for reading and I hope someone can help!
...Finally, if anyone knows of a better solution, please share! Again, I appreciate the help!
...There does not seem to be a way, here on StackOverflow.com to notify jockie to check out this thread. I wish there was a way to write to them or notify them, so that they could clarify for them-self or contribute to this thread as well. If someone knows of a way, please let me know that too!