creating a bar graph...

[mzimmers]

...two questions, one presumably simple, and the other a bit tricky:

1. The graph is to show 64 points on the X axis. How do I specify the "fatness" of my bars?

2. The boss says he wants every other value colored differently: red-blue-red-blue-red-blue...is there a way to do this?

What I'm actually plotting is 32 complex numbers. He wants the real component in one color, and the imaginary in another. So, 32 points of 2 values each is my 64 points total. 

Thanks for any assistance.

[Wolfgang]

1) I think you can't. Few years ago I have submitted a feature request here. You are invited to support it by giving it a kudos

2) Not directly. You could use two plots, one in red, one in blue. Or, with more effort, addressing both issues, you could use PlotRectangle....

[mzimmers]

Well...that's a bit unfortunate. How does this sound:

I'm thinking of having an expanded data array, in which each of my points occupies, say, 5 elements in the array. I guess I'd have to throw in a few empties between them, too, to provide some gaps. So, if my data array were:

[100, -1234, 1911...]

the array I'd pass to PlotX would be like:

[100, 100, 100, 100, 100, 0, 0, -1234,-1234,-1234,-1234,-1234, 0, 0, 1911, 1911, 1911, 1911, 1911...]

To get the bi-color effect, I suppose I'll have to change the gap sizes, and just overlay the two plots, right?

Any thoughts on this? I don't imagine the performance hit would be too terrible (at least for my purposes).

[mzimmers]

Update: for whatever reason, I was totally unable to get any variations on PlotX() to work for me. Here's one form of the call that I tried:

	plotHandle = PlotX(PANEL_MAIN, 
						PANEL_MAIN_TAPS_PLOT, 
						plotArray, 
						nbrPoints,
						VAL_INTEGER,
						//VAL_FAT_LINE,
						VAL_VERTICAL_BAR,
						//VAL_BASE_ZERO_VERTICAL_BAR,
						VAL_SOLID_SQUARE, 
						VAL_SOLID,
						1,
						VAL_RED);
	rc = RefreshGraph(PANEL_MAIN, PANEL_MAIN_TAPS_PLOT); 
						

 If anyone sees anything wrong with it, I'd appreciate a heads-up. I implemented a solution with rectangles that is adequate for now, but I'd still like to get the above code fixed.

Thanks.

[RobertoBozzolo · Accepted solution]

Shouldn't you call PlotY instead of PlotX?

Alternatively, if your graph is not autoscaling you may simply be missing the bars because they are out of visible range.

[mzimmers]

Oh, brother...I just love making stupid mistakes like that. Of course you're right, Roberto, and it works fine now. Sheesh...

I still don't like the 1-pixel wide "bars" though, and I think I'll use my rectangles instead. But thanks for furthering my CVI education a bit.

[RobertoBozzolo]

With reference to the bar thickness, it appears that the graph is a "smart control"  : it adapts bar width to actual data plotted.

Specifically, it appears that thickness is related to number-of-bars / axis-width ratio.

See this picture: the same CVI example with 100 and 10 data points plotted.

(Note: with thick bars you may have to struggle a bit to have the correct X scale shown. In the 10-samples example above, I enabled label strings for the graph X axis, used a scale of -0.5 to 9.5 and created the appropriate labels for integer values)

[mzimmers]

Thanks, Roberto. I guess the "smartness" in the control is something of a mixed blessing. I allowed enough space for the bars to be considerably wider than they were representing, so it appears that there has to be some threshold (which I didn't get to) of width in the plot area before CVI re-sizes the bars for you.

No matter, really, as the rectangles seem to be fine.

[RobertoBozzolo]

Can you attach a picture of your graph with vertical bars inside so that we can look at how they appear?

[mzimmers]

Sorry it took me so long to reply -- I've been stuck in TCP purgatory the last couple of days.

I guess they're not really too thin; I was just hoping for a little less space between the lines: