I have a C code that collects data and places them in a 2-D array. I would like to plot this data on an x-y graph (mathematics) automatically i.e. pass the data as parameters in a command line and get a graph
Are there any suggestions for how to do so?
gnuplot is a good one to look at assume you mean x-y charts, if you want actual graphs then look at dot
gnuplot will do what you need. If you want to process the data before, you might want to try octave, which aims to be a matlab equivalen (still uses gnuplot as a frontend for graphing).
If you want even more control, you could write a script in python and use matplotlib.
Related
I can make 2D dimensional netcdf maps of some quantity. I open it in panoply and there is color map of that quantity. But I cannot visualize some boolean value.
Can I somehow mark particular grid points with some symbol on the map (it can be diamond, square, triangle... whatever), is there a way how to do it in Fortran90? I accept also python related help.
Again: I mean there would be color map (from real values) (which I can do) and at the same time some values will have e. g. triangle on it.
If I understand the question correctly, then you can easily do that with Python and using some plotting library (e.g Matplotlib). With Fortran it is extremely tricky as it does not natively support plotting in my mind.
Basically with Python you just have to :
read the wanted variables (coordinates and the field itself)
make the map of the field i.e make the plot
find the locations you want to highlight and just add those locations to the plot
Hi i want to transform a image like this (right to left image ):
I have searching about functions like cvCartToPolar but i dont know how to use it..
Can someone help me? :)
nowadays, there is cv::warpPolar and if you can't achieve what you want (because for example your input image is only part of a disk, you might be interessed in cv::remap (the former uses the later internally).
In the later case, you have to build the mapping table yourself with some math.
If there is a given 2d array of an image, where threshold has been done and now is in binary information.
Is there any particular way to process this image to that I get multiple blob's coordinates on the image?
I can't use openCV because this process needs to run simultaneously on 10+ simulated robots on a custom simulator in C.
I need the blobs xy coordinates, but first I need to find those multiple blobs first.
Simplest criteria of pixel group size should be enough. But I don't have any clue how to start the coding.
PS: Single blob should be no problem. Problem is multiple blobs.
Just a head start ?
Have a look at QuickBlob which is a small, standalone C library that sounds perfectly suited for your needs.
QuickBlob comes with a small command-line tool (csv-blobs) that outputs the position and size of each blob found within the input image:
./csv-blobs white image.png
X,Y,size,color
28.37,10.90,41,white
51.64,10.36,42,white
...
Here's an example (output image is produced thanks to the show-blobs.py tiny Python utility that comes with QuickBlob):
You can go through the binary image labeling the connected parts with an algorithm like the following:
Create a 2D array of ints, labelArray, that will hold the labels of the connected regions and initiate it to all zeros.
Iterate over each binary pixel, p, row by row
A. If p is true and the corresponding value for this position in the labelArray is 0 (unlabeled), assign it to a new label and do a breadth-first search that will add all surrounding binary pixels that are also true to that same label.
The only issue now is if you have multiple blobs that are touching each other. Because you know the size of the blobs, you should be able to figure out how many blobs are in a given connected region. This is the tricky part. You can try doing a k-means clustering at this point. You can also try other methods like using binary dilation.
I know that I am very late to the party, but I am just adding this for the benefipeople who are researching this problem.
Here is a nice description that might fit your needs.
http://www.mcs.csueastbay.edu/~grewe/CS6825/Mat/BinaryImageProcessing/BlobDetection.htm
i would like to know how can i cut a jpg file using a coordinates i want to retrieve using artoolkit and opencv, see:
Blob Detection
i want to retrieve coordinates of the white sheet and then use those coordinates to cut a jpg file I'm took before.
Find this but how can this help?
How to slice/cut an image into pieces
If you already have the coordinates, you might want to deskew the image first:
http://nuigroup.com/?ACT=28&fid=27&aid=1892_H6eNAaign4Mrnn30Au8d
This post uses cv::warpPerspective() to achieve that effect.
The references above use the C++ interface of OpenCV, but I'm sure you are capable of converting between the two.
Second, cutting a particular area of an image is known as extracting a Region Of Interest (ROI). The general procedure is: create a CvRect to define your ROI and then call cvSetImageROI() followed by cvSaveImage() to save it on the disk.
This post shares C code to achieve this task.
First post here. Using C in Visual Studio 2008. Can work with VS 2005 if necessary.
How do I display numerical data in arrays as in a spreadsheet?
How do I plot numerical data in arrays?
These seem to be simple questions. But I cannot find solutions. So far, I would print the data to a file, import into Excel and view/plot. However, with this code there are too many arrays--so the print/import/plot is tiring.
Some constraints.
I do not want to write 20+ lines of code to do the above. MATFOR or Array Visualizer let you do the plotting with a one line function call.
They cannot display the data in a convenient format. I would like to display the data and the plot in one or two windows so that they are visible simultaneously.
This is a win32 console application---all the code is portable.
Will be using these during debugging.
Free or paid.
While I am looking for something specific, the requirements are substantially the same for any one doing numerical work with arrays and matrices--displaying data and plot simultaneously.
I am hoping that a such a tool has been written and is available.
I am also open to a solution that outputs the array data to an Excel sheet (can keep Excel open) and if it can also plot that can be great but I can live without plotting.
PS: I need this only when debugging the code.
I use ArrayDebugView which is a plug-in you install in Visual studio and draws graphs out of arrays while you are debugging your application. It works as a visual way of variable watch in debug mode. You don't need to write a line of code.
I can't think of any library that would enable what you want in a console app in less than 20 lines of code. My suggestion would be instead to script the plotting-step using MATLAB og GNU Octave to do the actual plotting.
In order to display numerical data in array, you should add the pointer to the first data element you want to observe, into the watch --- if you want to observe the array from the beginning, it would just be the array name, which is the pointer to the first element. In order to view more then one element, you add a "," after the pointer, followed by the number of element you want to observe.
For example, in order to observe the elements of float farray[100];, you should add to the watch farray,100.
In order to plot, you can copy-paste from the watch to your plotting software (i.e. excel), but it is not very convenient as you cannot copy the data column alone, but the columns to the left and right as well, so it involves extra manual editing.
I use GNUPlot (http://www.gnuplot.info/) to display my performance/speedup measurements.
I print my numbers to stdout and wrote a bash script that combines these numbers and calls gnuplot for rendering.
I made a simple plotting program for that purpose. There is only a textbox where I paste the data and a chart where it's drawn.
The data needs to be in either form:
with an automatic X (increment by 1 for each value): seriesName value
for both X and Y specified: seriesName xvalue yvalue
Most of the time I used to plot data from tracepoints.
I copy/paste the whole output window of VS, the plotting program ignores anything that doesn't follow these 2 forms (so I don't have to cleanup the string and put it in excel and all).
It does line, point, colum, area charts and save image, copy to clipboard.
MiniPlot
There are several ways to do this but this will require writing some code. Visualizing data is generally easy and straight forward but visualizing data exactly the way you want them to look will require some additional code and work.
There are several options to visualize data:
A combination of BASH and GNUPLOT
Use MATLAB or OCTAVE for all your calculations and visualization
Use PYTHON and SciPy and matlibplot libraries.
Gnuplot is a great tool to plot data but it is cumbersome to use. It looks fabulous if you invest time to get the plots right and combines excellent with LaTeX and has a good fit implementation for arbitrary functions. Visit http://gnuplot-tricks.blogspot.ch/ great site to learn all about gnuplot.
Numerical programs such as MATLAB and it's open source equivalent OCTAVE are great because they are fast implementation languages for numerical programs and have extensive additional libraries especially MATLAB. For high load numerical computing it is really slow and the plot library is only good for basic plotting needs.
Using PYTHON and its scientific programing libraries (SciPy and matlibplot) are a great combination. This allows excellent plot which are not as cryptic as gnuplot to plrogram and it is more flexible than MATLAB in plotting. Additionally it gives you a environment for numerical programing like MATLAB.