Append Column to Spreadsheet

[tdb867]

Hello, everyone.

As the title suggests, I'm looking to append a relative timestamp column to the spreadsheet I've created. I've had some difficulty with this due to the nature of the program, so let me go into a bit more detail.

The program I've written is a Producer/Consumer Loop which samples an analog waveform and exports it to a spreadsheet at discrete and triggered intervals. I've done this because I need better resolution that software timing can typically provide. So far so good, however, I would like to eventually append both a retriggerable elapsed time column (0-200ms for each sample) and a sample iteration column. Additionally--and a little further down the line--I would like to collect data on perhaps every other trigger event. I really only need to write a samply every now and again.

This would typically imply that I index each row of data and append the revised timestamp and sample iteration. I've attempted to use the Read from Spreadsheet VI to read into a for loop which appends the timestamp, but I feel as if this method is a bit superfluous. It seems I've run out of time for today, but if anyone has any bright ideas on how to accomplish any of these tasks I'll be up again tomorrow morning to take you up on it.

Thanks,

Travis

[Great_Britton]

Hey,

In this thread the issue is also covered. As GerdW says,

"You want to insert into the file, which means either:

- loading old data, convert to array, add new column, write to csv file (getting slower with each iteration)
- use buffering to hold all data in memory and write just once at the end of DAQ"

The best way to handle adding columns later is to use databases instead of spreadsheets, if that's a viable option. Otherwise you do have to read the data in, and then write it back out again after you edit it.

[altenbach]

You should append rows instead. You can always transpose at the very end. Rows can be appended without touching the existing file content, while appending columns always means that the entire file needs to be rewritten (the existing content need to be shifted around and the column data interlaced).

[tdb867 · Accepted solution]

Thanks you guys, I figured it out. I'll attach the code if anyone's interested.