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"Time" Signal?


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Hi Seeq,

I am new to Seeq and have two questions regarding the "Time" variable/signal. 

1. In csv file, the first column is always Date/Time, and this "time column" can be used in subsequent analysis (ex. derivative, avg, complex formula). I don't know how this "time column" is treated in Seeq (seems to me by default is the x-axis). Can we create a signal that include this time information?

2. How can time be used in correlating different signals? Let's say I have signals A&B and want to calculate a new signal C. Is it possible to do so in Seeq?

Time A  B C
t1 a1 b1 -
t2 a2 b2 =(b2-b1)/(a2-a1)
t3 a3 b3 =(b3-b2)/(a3-a2)

Thanks for your help!
Yanmin

 

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  • Seeq Team

Hi Yanmin,

For your first question, yes your time column is treated as the x-axis in Seeq. As a result, every signal that is trended in Seeq naturally incorporates this time column as its x-axis. When you say "create a signal that includes this time information" are you thinking of having time on the y-axis as well?

For your second question, yes we can. Seeq has a function called runningDelta(), which calculates the difference of successive samples. So in your scenario, (b2-b1) would be captured by $b.runningDelta(). (b2-b1)/(a2-a1) would also be $b.runningDelta()/$a.runningDelta(). This would all be done in Seeq's Formula tool. Hopefully the example screenshot below helps.

image.png

If you'd like help understanding or would like to discuss more, please come to our office hours where a member of our team can help you. https://info.seeq.com/office-hours

Regards,

Kris

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Hi Kris,

Thanks for the reply. 

In reality, different signals may have different frequencies. And sometimes there is lack of data for a period of time just due to measurement failure. 

Time  Signal A Signal B
t1 a1 -
t2 a2 b1
t3 failure -
t4 a4 b2

So for question 1,  what I was thinking is to check if we have data at a specific time. In csv file, we can filter the time we wanted, and check the data. Is it possible in Seeq?

For question 2,  if I want to create signal C=(b2-b1)/(a4-a2), how should I deal with it? Can runningDelta() help?

Thanks!

Regards,

Yanmin

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  • Administrators

Hi Yanmin-

Question 1: You can find more information about the CSV import tool in our Knowledge Base: https://seeq.atlassian.net/wiki/spaces/KB/pages/537690127/Import+CSV+Files+2.0.  When you use this tool to import data, you can specify how you would like Seeq to handle "invalid" data (like the failure or null values you described).  For the example you provided, I think you would want to select "Skip".

image.png

Once the data is imported Signals A & B will only have data points where there is valid data. 

Question 2: The .runningDelta() operator calculates the difference between adjacent samples, as you described in your post.  More information can be found in the Formula documentation.

image.png

 

Please let me know if you have any additional questions.

Thanks,

Lindsey

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