M Language - convert duration to seconds

[BigPatJennings]

Apologies, but I really don't know M at all and I've run into difficulties with time and duration. I have a table with, amongst other things, 15 columns of durations in the format xx:xx:xx . I currently have these 15 columns as a strings. I'd like to know the custom function to convert this to seconds - i.e., (number before first : delimiter * 3600) + (number between first and second : delimiter *60 ) + number after last delimiter.

I can do this in Excel with LEFT, MID, LEN and FIND, and I guess I could do the same as calculated columns in DAX, but I don't know how to do it in Power Query with M. Is it quicker to do it that way?

I haven't upoad a pbi file here as I'm hoping it's quite a self-explanatory question.

Many thanks

[ronrsnfld]

You can either add a column or transform the existing column.

 - Ensure your dataColumn is type as a duration

 - To add a column, navigate to the Add Custom Column item and, for a formula:

    =Duration.TotalSeconds([dataColumn])

[HotChilli · Accepted solution]

If you look on the right hand side of this web page, you'll see a 'Recommendations' panel and they might help you.

Alternatively, if you get the column into a duration data type, you can use function:

https://learn.microsoft.com/en-us/powerquery-m/duration-totalseconds 

[BigPatJennings]

Thanks. They're all about how to do it in DAX though, and I think I can do that. I'm trying to do it in M/Power Query, rather than going through the process of 'copy column, split by delimiter, do arithmetic, delete columns again' 15 times. Sorry, guess I'm being lazy!