Linear interpolation with unevenly spaced data

[WE5T]

Hi,

I am trying to interpolate a data set to 1 second intervals. The original data set is unevenly spaced i.e. 1, 3, 5, 6, 8, 9 etc. I have attached an example data sheet.

Column A = Time (s)
Column B = Value

Column D = Interpolation Time Value (i.e. 1 s intervals)
Column E = Interpolated Value.

If you could provide an excel equation for column E it would be much appreciated. Please feel free to edit the spreadsheet layout if this makes it easier.

Interpolation Spreadsheet Example.xlsx

Many thanks,

Andy

[zbor]

Here, try this:

[Pete_UK]

Put this in E3:

=IF(ISNUMBER(MATCH(D3,A:A,0)),INDEX(B:B,MATCH(D3,A:A,0)),(INDEX(B:B,MATCH(D3,A:A))+INDEX(B:B,MATCH(D3,A:A)+1))/2)

then copy down.

Hope this helps.

Pete

[zbor]

Much simplier than mine but mine works for more than one missing value:

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[Pete_UK]

Yes, mine is just a straight average for the missing values, whereas yours seems to take a weighted average so gives a smoother transition.

Pete

[WE5T]

Hi Zbor and Pete,

Thank you both for your response. Zbor, the equation works perfectly and will certainly save me plenty of time.

I was wondering whether I could ask you if you could take a look at the new spreadsheet I have attached. It is the same as the initial one except I have added 13 extra columns that I would also like to be interpolated to 1 s values. I have included 4 columns with no data which I may add in later. If you could set the spreadsheet up so that whatever data is inserted into these additional columns is also interpolated that would be fantastic. I have tried to replicate the equation that you have included to the additional columns but have had no luck!

Thank you again to both of you for your help on this.

Much appreciated.

Andy

Interpolation Spreadsheet Example (1).xlsx

[zbor]

Try this:

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[WE5T]

Excellent.

Many thanks.

Andy

[GMS01]

Hi Zbor,

I'm wondering if it is possible to get a copy of this spreadsheet - I'm looking to do a similar interpolation to some data and looking for examples?

Thanks,
Glenn

[FDibbins]

Hi Zbor,

I'm wondering if it is possible to get a copy of this spreadsheet - I'm looking to do a similar interpolation to some data and looking for examples?

Thanks,
Glenn

The file can be accessed by clicking on the file name in that post