Convert time points to seconds

Question

Hi,

I have a dataset of EMG recordings consisting of 15 muscles (columns) and 6,000 time points (rows) for each muscle. The data was collected at 50 time points per second. I would like to know how I can convert the time points into seconds so that I can plot the muscle activity over time. I have attempted doing this manually but it takes extremely long, could someone give me some guidance please?

Answer 1

attempted using mm:ss,0 which is one of the option provided that appears the closest to your suggestion but this returned 00:00,0. Could you let me know where I am going wrong?

I use period ("full stop") for the decimal point. You use comma. So the correct format should be Custom m:ss,00 or [m]:ss,00 -- comma after "ss".

You can use "mm" if you want to see 01:23,02 (leading zero).

And you can omit the square brackets ("[...]") if you are sure that minutes ("m") will not exceed 59.

The format mm:ss,0 results in 00:00,0 for 0,02 (1/50) and 0,04 (2/50) because they round 0,0 seconds -- one decimal place. But 0,06 (3/50) should display 00:00,1 .

Note: I assume that you have a fully-functional version of Excel. The free version of Web Excel (onedrive.live.com) is not fully-functional. In particular, I believe that it does not support all of the numeric formats.

Also, I am not familiar with Mac versions of Excel. They might not be fully-functional, either. I do not know.

If you still have problems, I might need to see an example Excel file that demonstrates the problem. Upload the example file to a file-sharing website, and post the download URL in a response here. I like box.net/file; others like dropbox.com. You might prefer onedrive.live.com because it shares the login with this forum. But I worry that "onedrive" might alter the Excel file sometimes.

Answer 2

Hi Joeu2004,

Thank you for your response, I really appreciate it.

I used =A1/50/86400 and tried formatting it as custom [m]:ss.00. However, I got the error message I have included below. I then attempted using mm:ss,0 which is one of the option provided that appears the closest to your suggestion but this returned 00:00,0. Could you let me know where I am going wrong?

I would like to plot the muscle activity over the 120 seconds as you mentioned.

![](https://learn-attachment.microsoft.com/api/attachments/e166287b-baf4-42ef-9ef3-5f9206dbfcaf?platform=QnA

Answer 3

First, it might be better leave the time data as "time point indexes", which I assume are 1 to 50 in the first second, 51 to 100 in the second second, etc. Generally, it is better to work with integers than with "real numbers" like 0.02, 0.04, etc.

But if you want decimal seconds like 0.02, 0.04, etc, you can enter formulas of the form =A1/50 into a parallel column.

Alternatively, if you want Excel times that you might display as m:ss.00 (6000 time points is 120 seconds; 2 minutes), the formulas can be of the form =A1/50/86400, because there are 86400 seconds in a day. Format as Custom [m]:ss.00. The square brackets are prudent, albeit not required with this data.

Finally, if you want to convert the time points in situ, enter =1/50 or =1/50/86400 into a cell, press ctrl+c to copy it, select the range of time points (e.g. A1:A6000), right-click and paste-special-multiply. Format A1:A6000 appropriately.