I'm trying to read a pgm file in R. I set my wd to where the image is and then simply try to read it:
setwd("~/3 Diplomado/5 Multivariado/lfwcrop_grey/faces")
library(pixmap)
x <- read.pnm(system.file("Aaron_Guiel_0001.pgm", package="pixmap")[1])
But I get the following error:
Error in if (ch == "#") { : argument is of length zero
In addition: Warning message:
In file(file, open = "rb") :
file("") only supports open = "w+" and open = "w+b": using the former
Not sure what it is. I think it simply doesnt find the image.
What am I doing wrong? any hints? Thank you in advanced!
J.
Simply try this one:
x=read.pnm(file = "Aaron_Guiel_0001.pgm")
The system.file() is used to find the full path of the files included in packages. It is used in the package example, but you don't need to use it while reading your own file.
Related
I was trying to print a backtrace using dladdr(). info.dli_fname in the following code snippet is displaying the file name of an ELF file. Could you please tell me if it is possible to resolve and print the name of the source file and line number programmatically without the help of addr2line or gdb?
Code:
void print_caller(void)
{
int rc = -1;
Dl_info info = {0};
void *pc = __builtin_return_address(0);
rc = dladdr(pc, &info);
printf(" ==> %p: %s (in %s)\n", pc, info.dli_sname, info.dli_fname);
}
Output:
$ ./a.out
==> 0x55a6b04a1589: foo2 (in ./a.out)
tell me if it is possible to resolve and print the name of the source file and line number programmatically
It is definitely possible -- addr2line and gdb do that.
But it is very non-trivial -- it requires understanding and decoding (possibly multiple) complicated debugging info formats.
If you only care about a single platform (looks like Linux), things are a bit easier -- you only need to decode DWARF.
But that format is still pretty complicated. You should start with a helper library, such as libdwarf.
I'm using protobuf and I'm generating JAVA classes from the following proto file.
syntax = "proto3";
enum Greeting {
NONE = 0;
MR = 1;
MRS = 2;
MISS = 3;
}
message Hello {
Greeting greeting = 1;
string name = 2;
}
message Bye {
string name = 1;
}
option java_multiple_files = true;
Now I need to add some code to the generated files and I found that is possible using a custom plugin (https://developers.google.com/protocol-buffers/docs/reference/java-generated#plugins). I'm trying to generate that plugin in Java, something like this.
public class Test {
PluginProtos.CodeGeneratorResponse.getDefaultInstance();
/* Code to get generated files from java_out and use the insertion points */
codeGeneratorResponse.writeTo(System.out);
}
And then I run
protoc --java_out=./classes --plugin=protoc-gen-demo=my-plugin --demo_out=. example.proto
The problem is that on my Test.java main method I don't know how to get access to the files created by the option --java_out so that I can use their insertion points. Currently the CodeGeneratorResponse for the default instance is empty (no files).
Does anybody know how can I get the CodeGeneratorResponse from the --java_out so that I can add more code to the generated classes?
Thanks in advance.
I recently struggled with this as well and wasn't able to find a good answer. I finally figured it out after staring at the comments within the CodeGeneratorResponse message for a while.
What threw me off at first was that I was thinking of plugins as a pipeline, where the output from one feeds into the next. However, each plugin gets the exact same input (the parsed .proto files expressed via CodeGeneratorRequest messages), and all the generated code from the plugins (including the built-in ones) gets combined into the output file. However, plugins may modify the output from the previous plugins, which is what insertion points are designed for.
Specifically to your question, you would add a file to the response with the name field getting set to the name of the generated Java file, the insertion_point field getting set to the name of the insertion point at which you want to add code, and the content field getting set to the code you want inserted at that point.
I found this article helpful in creating a simple plugin (in this case in python). As a simple test, I modified the generate_code function from that article to look like this:
def generate_code(request, response):
for proto_file in request.proto_file:
f = response.file.add()
f.name = "Test.java"
f.insertion_point = "outer_class_scope"
f.content = "// Inserting a comment as a test"
Then I ran protoc with the plugin:
$ cat test.proto
syntax = "proto3";
message MyMsg {
int32 num = 1;
}
$ protoc --plugin=protoc-gen-sample=sample_proto_gen.py --java_out=. --sample_out=. test.proto
$ tail -n3 Test.java
// Inserting a comment as a test
// ##protoc_insertion_point(outer_class_scope)
}
Your plugin just needs to be some executable which reads a CodeGeneratorRequest message from stdin and writes a CodeGeneratorResponse message to stdout, so could certainly be written in Java instead. I just chose python as I'm generally more comfortable with it and found this simple example.
As a reference, here's a plugin I wrote for generating code based on custom protobuf options.
I have made a custom python plugin.
To run my plugin i use the command below:
protoc --plugin=protoc-gen-custom=my_plugin_executable_file --custom_out=./build test.proto
So i think that, you have to generate an executable file from your .java file and use it in your command.
I'm writing a Mac OS program, and I have the following lines:
os.execute("cd ~/testdir")
configfile = io.open("configfile.cfg", "w")
configfile:write("hello")
configfile:close()
The problem is, it only creates the configfile in the scripts current directory instead of the folder I have just cd' into. I realised this is because I'm using a console command to change directory, then direct Lua code to write the file. To combat this I changed the code to this:
configfile = io.open("~/testdir/configfile.cfg", "w")
However I get the following result:
lua: ifontinst.lua:22: attempt to index global 'configfile' (a nil value)
stack traceback:
ifontinst.lua:22: in main chunk
My question is, what's the correct way to use IO.Open to create a file in a folder I have just created in the users home directory?
I appreciate I'm making a rookie mistake here, so I apologise if you waste your time on me.
You have problems with ~ symbol. In your os.execute("cd ~/testdir") is the shell who interprets the symbol and replaces it by your home path. However, in io.open("~/testdir/configfile.cfg", "w") is Lua who receives the string and Lua doesn't interprets this symbol, so your program tries to open a file in the incorrect folder. One simple solution is to call os.getenv("HOME") and concatenate the path string with your file path:
configfile = io.open(os.getenv("HOME").."/testdir/configfile.cfg", "w")
In order to improve error messages I suggests you to wrap io.open() using assert() function:
configfile = assert( io.open(os.getenv("HOME").."/testdir/configfile.cfg", "w") )
I have been trying to read a jpeg file using PIL in python 3.4. I need to save this file into string format. Although some options are provided on this site but I have tried a few but it is not working. Following is my code snippet which i have found on this site only:-
from io import StringIO
fp = Image.open("images/login.jpg")
output = StringIO()
fp.save(output, format="JPEG")
contents = output.getvalue()
output.close()
But i am facing the following error :-
TypeError: string argument expected, got 'bytes'
Could you please suggest what I have done wrong and how to get this working?
In python 3 you should use a BytesIO,
whereas as read in python docs:
StringIO is a native in-memory unicode container
.
Thanks a lot for the hint. I Actually have a found a different way of reading the image file and storing in string object in python2.x . Here is the code. Please let me know if there is any disadvantage of using this.
imgText = open("images/login.jpg", 'rb')
imgTextStr = imgText.read()
imgText.close()
I am trying to read a gist containing a dput from Github:
library(RCurl)
data <- getURL("https://gist.githubusercontent.com/aronlindberg/848b8efef154d0e7fdb4/raw/5bf4bb864cc4c1db0f66da1be85515b4fa19bf6b/pull_lists")
pull_lists <- dget(textConnection(data))
This generates:
Error: '\U' used without hex digits in character string starting ""## -1,7 +1,9 ##
module ActionDispatch
module Http
module URL
- # Returns the complete \U"
Which I think is a Ruby error message rather than an R error. Now consider this:
data <- getURL("https://gist.githubusercontent.com/aronlindberg/b6b934b39e3c3378c3b2/raw/9b1efe9340c5b1c8acfdc90741260d1d554b2af0/data")
pull_lists2 <- dget(textConnection(data))
This seems to work fine. The former gist is rather large, 1.7mb. Could this be why I can't read it from Github. If not, why?
The gist that you created does not have a .R file in it, since pull_lists does not have an extension. I forked your gist to this one and added the extension. Now it is possible to source the gist and save it to a value.
library("devtools")
pull_lists <- source_gist("a7b157cec3b9259fc5d1")