How do I plot the output from a C++ Win32 console app?

Question

I have a small Win32 console application which is essentially a test harness. I read data in, do some processing on it and currently just output some of the numbers to the console. This isn't a huge problem - I can get an idea of what the data looks like, but it would be much easier to analyse if there was a way of getting that information into a graph for each run of the software.

I've been getting to grips with GNUPlot recently, but can't work out a simple way to get the data sent to it. Has anyone tried this? ..or is there another graphing application I should try?

Excel and OO Calc are great tools and I've loaded .csv data into them for graphing data plenty of times myself. I was, however, hoping for a way to dynamically pipe data into a graphing application to avoid having to close/reopen excel and plot a graph each time I want to look at some data.

I think you can pipe data into GNUPlot (which is why I mentioned it) but the details of how to do so are rather scant.

Answer 1

You don't really need to touch VBA to do this

In Excel you can set up a Data Connection to a file, it supports many files type but CSV does work fine.

• Go to List item
• Data Tab
• Click Connections
• Click Add
• select the file
• go to the connection properties - un-tick prompt for file name
• set the required period.
• close the connections dialog
• select the start cell for importing the data - cell 1a on worksheet 2
• click existing connections
• select you data connection
• flip to worksheet1 add your chart and hookup the data.

the chart will now update automatically

this is Excel 2007 - but think older version had this and I think OO can do it to.

Answer 2

A simple approach is to wtite the data out as CSV and then import it into a spreadsheet like Excel or OpenOffice to do the graph drawing.

Edit: Following your question, I got interested in GNUPlot myself - this is the simplest description of using it from the command line that I found: http://www.goldb.org/goldblog/CommentView,guid,f378e279-eaa5-4d85-b7d2-0339a7c72864.aspx

Answer 3

Never underestimate the power of Excel and a .csv data dump.

Writing data to a .csv file form C++ is not very difficult and there's lots of articles out there regarding the subject, for example: here, or just google.

Excel can easily load .csv's and then you can just use that to plot whatever graphs you require. THis is particularly useful if you just want a quick visual sanity check of results etc.

Answer 4

You might also want to look into XMGrace which allows you to launch it and drive it dircetly from C/Fortran programs as shown here

Answer 5

Excel is completely script-able. Use the macro recorder to figure out the steps. Create the chart in its own sheet. Then save the chart using the GIF filter.

The actual import is something like:

ActiveChart.Export FileName:=something_dot_gif, FilterName:="GIF"

Answer 6

I just found an example of piping data into gnuplot on Cardiff University's website. Not tried it yet, but it looks promising!

[edit] ..and another which includes some notes for windows.

Answer 7

You can use MathGL - it can create a window (FLTK, GLUT or Qt) and display plot inside. Also it have large set of plot types and can work in console.