Zero on Graphs

Hi All,
I have this Line Graph:
I want to have a 0 instead of a gap in a Line Chart.
For example, on 6/10 the GIFT_D line should continue with the value 0 instead of having a gap, same with 6/23, 6/8, etc...
The ghaph corresponds to this Pivot table (Char Pivoted Results):
The Table view result (I think that if I modify the repository adding a LEFT OUTER JOIN to get for each day all the gift types, it will work. But I don't want to do this because the normal behaviour should be INNER JOIN, this is only a special requirement for a specific report):
So is it possible to get zeros instead of gaps without modifying the repository?
ps. I managed to show zeros instead of nulls in Pivot table but the chart is still showing gaps (http://total-bi.com/2010/10/replace-nulls-in-obiee-pivot-table/)
Thanks in advance,
Regards

Hi,
Changing data type to replace null with 0 will change only display value, not actual value. So please use ifnull in the column formula to actually replace null with 0. This '0' value then will be reflected in charts as well.
Regards,
~Karbhari

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WPF graph children z-order

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Solved!
Go to Solution.

Set the ZIndex of the canvas to a value above the default of zero:
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Hi Everyone,
I have a main and a sub-vi to plot 2 scalar numbers at the time using the graph control (LV8.5), and is not working correctly as I will expect to work. Basically the main vi has a graph that is updated everytime its sub-vi is called. However it looks like the shift registers keep "its memory" alive even though the sub-vi has finished or stopped.
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Attachments:
ChartingTwoNumbersAtTheTime_SUB_VI.vi ‏15 KB
ChartingTwoNumbersAtTheTime.JPG ‏83 KB
ChartingTwoNumbersAtTheTimeMainVI.vi ‏15 KB

Since you are using LabVIEW 8.5, you can use feedback nodes in the subVI without the need for any while loop. Now use a case structure connected to the "first call?" primitive as e.g. in the attached modification.
You should not place a wait in the subVI, this make no sense. There is no reason for the sequence frame. You also don't need to zero the graph in the main VI as you currently do.
LabVIEW Champion . Do more with less code and in less time .
Attachments:
ChartingTwoNumbersAtTheTime_SUB_VIMOD.vi ‏15 KB
ChartingTwoNumbersAtTheTimeMainVIMOD.vi ‏14 KB

How to measure time difference between zero crossing of a sine wave and rise time of a pulse on a same graph?

I have a 50Hz sine wave and a pulse signal on a same graph. The phase difference between two is between 0-90 degrees.
Now I need to calculate the time difference between (when the sine wave crosses zero volts) and (when the pulse rises). The frequency will stay approximately same for both signals.
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Message Edited by awais.h on 03-30-2010 11:20 PM
Message Edited by awais.h on 03-30-2010 11:21 PM
Solved!
Go to Solution.

Hi
Thanks for the code but I'm afraid it won't work. Like you said the probability of choosing a value that is on both graphs may not happen. This is something that I would like the code to do automatically.
But I did use the previous code posted and made some modifications to it and it seems to work perfectly. Now the next thing is to be able to get just that one value that tells you the first time difference.
Here is what I get using that code.
As you can see from the t Values. I only need the one that is highlighted. If there is a way to filter out the rest it would be great.
I was thinking of a while loop and as soon as the value is higher than 3E-5 it would store the number and stop the loop, but I'm not too familiar with arrays in labview.
Here is the the code modified.
As you can see, it wasn't that big of a modification and it still is your code.
I will keep trying.
Thanks for the help
Attachments:
FinalShockSpeed.vi ‏55 KB

Chart Web Part to not plot zeros on a line graph

Hi all,
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Iam using a table in numbers to plot daily graph lines. If I fill a cell with a text box at say zero it plots the graph. I can't actually set the cell value until the actual day but the graph plots it at zero when I don't want it to plot anything. Is tho

I am using a table in Numbers to plot daily graph lines. Mood swings of how I am on the day, i"m a depressive.
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The answer is (sort of) in your subject, but edited out of the problem statement in the body of your message.
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Regards,
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Graph weekly scrap summary with zero value.

Post Author: Phoebe
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Hi Markus,
Thanks !!!
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Graph axis Zero is not Zero

Hi,
I plot data on a graph in SI unit. Sometimes the 0 of the y-axis shows a very small number but not zero.
This is super ugly and annoying.
I saw that somebody complained about that 4years ago: http://forums.ni.com/ni/board/message?board.id=170&message.id=47417&requireLogin=False
I use 8.5 and this "bug" is still there!
Is there a fix or a work around?
thanks
Attachments:
Axis Zero.png ‏12 KB

I agree, this is a real pain !!!
The workaround was given by Greg McKaskle : Try changing the axis format. Avoid autoscaling.
Chilly Charly (aka CC)
E-List Master - Kudos glutton - Press the yellow button on the left...

Splitting up plots on XY Graphs depending on zero crossing

Hi,
I posted this question earlier and thought I got a solution. Please read the old thread: http://forums.ni.com/ni/board/message?message.uid=1098899#U1098899
Basically, my problem now is that the way its being done now, whenever it crosses the zero axis with a negative slope, it temporarily creates another plot and as soon as it crosses it with a positive slope, it merges those 2 graphs together. So somewhere between the slope going from -'ve to +'ve and crossing the zero, I have an extra plot, and it distorts the colors of my plots, which seems like a bug to the user and may confuse them. I have attached a VI below where you can see this behavior in the 2D array indicator.
Attachments:
XY Example VI.vi ‏18 KB

I don't know what your intentions are with this VI, or what you mean by "temporarily creates another plot".
You've got a lot of array manipulation going on inside those loops. You are just going to have to sit down, figure out how those loops are currently working, and how to change them if they aren't doing what you want.

Zero crossing, "Triggering" and XY-Graphs

I'm trying to measure the electrical hysteresis of a sample. The way in which I do this is by measuring two voltages within a circuit, sending them to my DAQ, and then plotting them in an XY-Graph to view the shape of the curve. I can somewhat see the hysteresis, but II need to measure the "zero-crossings"; that is to say, the value of one function, when the other is 0, and vice versa. So when V1 = 0, I want to know what V2 is, and when V2 = 0, I want to know what V1 is. Seems simple enough, and I have included my VI.
First I tried the ZeroCrossingPtbyPt, along witha Relay, which never seemed to trigger properly.
Second, I tried using Trigger and Gate, but that seems to give inflated values.
This VI can be tested by removing the DAQ assitant and replacing it with two "Generate Signal"(s), with the same frequency, different amplitudes, and a small phase difference, and this will produce a similar effect without the real signals.
Next, I am sending the raw voltage signals into a Waveform Graph. However, it is impossible to get the traces to stay "still" on the graph. In other words, if this were a real oscilloscope, there would be a "triggering" problem, and if the trigger were set to the proper value, the oscilloscope would be able to track the waveform without it jittering left to right in time. Any ideas on this? I've tried to change just about everything in the Waveform Graph with no difference. Do I need to send in some other signal to get the graph to follow the waveform properly? This is really important because it will tell me if my sample rate is good enough to capture the signal (a sine wave at 1 kHz).
Finally, the hysteresis curve on the XY Graph seems to cover many cycles (periods) of the waveform, but I want it to cover only 1 cycle at a time, so it isn't so sketchy-looking. It's very boxy as well. So in short, the number of points it is plotting is fine, but it is not plotting them quickly enough, since I'd like all of the points it plots to be over a single period of the waveform.
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Attachments:
hysteresis.vi ‏176 KB

As it turns out, the issue was that I was not collecting enough samples at a high enough sample rate from the DAQ. This is why it worked with "Generate Signals" and did not work with the DAQ Assistant. Because there were not enough samples, the apparent zero crossing was occuring either too early or too late, leading to an incorrect value. Therefore, the best solution when it comes to finding zero crossings is make sure your # of samples, and sample rate are high enough to get an accurate measurement.
As a result, this is why my XY Graph was showing blocky hysteresis loops, rather than nice smooth curve hysteresis loops. The data being sent to it was not quick enough, and therefore the XY- Graph connected the dots between the points that it was sent, yielding a truncated loop, which appeared blocky or sketchy.
On the issue of triggering, this can apparently be set within the DAQ Assistant in the "Triggering" tab; the key is chosing the correct channel to trigger from, and a reasonable trigger level. This was my problem, and this is why my Graph appeared to jitter. It was not the graph itself, but the DAQ Assistant that did not tell it the proper triggering timing.
So, in short, I solved my own problems, but I leave this as a record for those who encounter similar problems in the future.
Thanks.

Do you know a VI to detect numerical zeros in a graph?

I need to detect numerical zeros in a graph and I don't know the analytical formula of the function represented on the graph.

If you just want to detect zeros in the array that represents the graph just search the array for zeroes...However if you want to detect zero crossings you can do it as described here:
http://exchange.ni.com/servlet/ProcessRequest?RHIVEID=101&RPAGEID=135&HOID=5065000000080000008B2B0000&UCATEGORY_0=_49_%24_6_&UCATEGORY_S=0&USEARCHCONTEXT_QUESTION_0=Zero+crossing&USEARCHCONTEXT_QUESTION_S=0
A similar example can be found on:
http://sine.ni.com/apps/we/niepd_web_display.DISPLAY_EPD4?p_guid=B123AE0CB8F6111EE034080020E74861&p_node=DZ52028&p_submitted=N&p_rank=&p_answer=&p_source=External
Or if it fits you task; use the in-build zero crossing point by point detector that comes with LabVIEW...
If you do it by detecting changes in sign you can interpolate
between the two points to find the exact position of the crossing. Attached is an example that does just that.
MTO
Attachments:
zerocrossing_Interpolated.llb ‏22 KB

Multiplot graph with missing values fills them with zero instead of NaN

I have a waveform graph with multiple arrays (2D) which has different numbers of points in each array. LabVIEW finds the array with the most points and then plots all arrays with that many points. It assigns the missing points a value of zero and displays those zero values. This means arrays with fewer points than the maximum will have values of zero appear in their plots. This can be avoided by filling in missing points with NaN. I am acquiring data in a loop and displaying it which requires continuous determination of the number of actual points and filling in of missing points with NaN. Not difficult, but this could be avoided if LabVIEW would fill missing points with NaN instead of with zero. Any way to have this happen automatically ?
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Attachments:
Graph MultiPlot Missing Data.vi ‏18 KB

You can also consider using an XY graph so you don't have to do additional data manipulation. See attached for comparison.
Attachments:
Graph MultiPlot Missing Data mod.vi ‏22 KB

Graphing History to not drop to Zero

We are on 4.1 PL9. We have a requirement where the history value should not drop to zero in the graph. INstead it should stop at the point in the last time bucket where there is a non-zero value. Similarly Forecast in the graph should start from current bucket that will typically have non-zero value. The options in the graph do not seem to work and even horizon specific initialization to the Keyfigures does not do the trick. Any suggestions welcome to achieve this requirement.Unfortunately 4.1 does not discriminate a null and a zero.

Dear Srinivas,
I suugest you to use an auxiliar K-F just to graph, then implement a Macro to "interpolate" values for the K-F if zero is between two values you can assign an average instead of zero.
Best regards,
Carlos Rodríguez

How to avoid the zero readings entering into graph

I'am attaching one VI.Here I 'am trying to combine three numbers from the termination part of the motor for finding the steps it rotated. So the numbers 165,166, 167 in the combination given in VI will provide me the necessary number.I need a help that if I plot the graph whenever the running command is there the system will give me zero in XY graph. I need to avoid that problem. So how can I do it.please kindly reply
Attachments:
data aquisitio.14.6.13.11am.vi ‏110 KB

Many output tunnels of your stacked cases are set to "use default if unwired". The default value for a numeric is zero, meaning whenever one of thise cases execute, you'll end up with zero (bad value) instead of a data received from the instrument (good value). If you wire the data array across all cases, you can leave it unchanged in the cases where no data appears (simply wire the array across untouched), but append new values where you get actual data (in this particular situation if the outer case is true and the inner case is false).
You've been working on this for weeks now and have not followed any advice given here. If this challenges you so much, maybe programming is not what you should be doing.
LabVIEW Champion . Do more with less code and in less time .

Graph time axis start zero

Hi
I acquire signals from a USB card (N signals), I use de DAQmx Analog input (NchanelsNsamples) ,I dont know how i can start the time axis at zero..
please you can help me
thanks

Hello Alexandra,
If you are using a graph, you have just to double-click on the first value to change it.
If I don't answer your question, please give me more information.
Regards.
Jean-Baptiste C.
National Instruments France
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Zero on Graphs

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