Requesting Data from IADSDATAFILEINTERFACE
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Joe Young
May 4, 2012, 10:03:13 AM5/4/12
to IADS
I am working on a datahandler in Visual Basic (may convert over to C++
and create a dll to read into my VB program if it is faster but I am
happy with the speed so far) to read the raw IADS data files and
export/plot the data. The issue I am working on is trying to
synchronize all of the data so the data points are at the same "time."
If data is not available at the requested time we want to use the
previous available data point (ie "stale" data).
What I would like to do is use one start time from one parameter (more
then likely the run parameter, but will be user definable)
then .AdvanceTime to advance the time at the requested sample rate.
this array(value) would be used as the time array for plotting and the
"starttime" in the .ReadData.
I have implemented this scheme in a proof of concept code and it works
great, and I think it does what I want. When I look at the return time
from the .ReadData it appears to be the time requested or the sample
before the time requested (ran several cases).
The question I have is with the IADSDATAFILEINTERFACELib, will it
always return the previous sample, or does it return the closest value
(ie do I need to check to make sure that the time returned is not
ahead of the time requested)?
Thank you for your help.
Joe
and create a dll to read into my VB program if it is faster but I am
happy with the speed so far) to read the raw IADS data files and
export/plot the data. The issue I am working on is trying to
synchronize all of the data so the data points are at the same "time."
If data is not available at the requested time we want to use the
previous available data point (ie "stale" data).
What I would like to do is use one start time from one parameter (more
then likely the run parameter, but will be user definable)
then .AdvanceTime to advance the time at the requested sample rate.
this array(value) would be used as the time array for plotting and the
"starttime" in the .ReadData.
I have implemented this scheme in a proof of concept code and it works
great, and I think it does what I want. When I look at the return time
from the .ReadData it appears to be the time requested or the sample
before the time requested (ran several cases).
The question I have is with the IADSDATAFILEINTERFACELib, will it
always return the previous sample, or does it return the closest value
(ie do I need to check to make sure that the time returned is not
ahead of the time requested)?
Thank you for your help.
Joe
Michael Jones
May 4, 2012, 1:11:17 PM5/4/12
to ia...@googlegroups.com
Hi Joe,
Admittedly, I've never used the IadsDataFileInterface myself, but looking at the code it looks like if you request a sample from an 'arbitrary' time you will get the last known good value (LGV) from the preceding 'real' time value.
On the ReadData call, you can get the 'real' time of the data sample by examining the corresponding TimeArray value for each DataArray value.
Another way of phrasing it might be to think of the input time to the function as simply a suggestion (ditto for RequestedPoints) whereas the TimeArray (and ActualPoints) contain the definitive answer to your request.
I hope I got that right, if I didn't, one of the interface developers will likely catch it before the end of the day.
Admittedly, I've never used the IadsDataFileInterface myself, but looking at the code it looks like if you request a sample from an 'arbitrary' time you will get the last known good value (LGV) from the preceding 'real' time value.
On the ReadData call, you can get the 'real' time of the data sample by examining the corresponding TimeArray value for each DataArray value.
Another way of phrasing it might be to think of the input time to the function as simply a suggestion (ditto for RequestedPoints) whereas the TimeArray (and ActualPoints) contain the definitive answer to your request.
I hope I got that right, if I didn't, one of the interface developers will likely catch it before the end of the day.
Joe Young
May 4, 2012, 1:21:57 PM5/4/12
to IADS
Great sounds like it is exactly what I need. Thank you for your help.
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