13.2Linear Interpolation

[HillaryLansfield]

I have 2 tables, shown below. Table 1 is (sort of) a reference/look up table, where it shows what eff% is at a specific P (MW). Tables 2 has the values that need to be looked up, it only has P, and I would like to determine, what the eff% should be (based on table 1).

I will note, that in some cases

Table  1:

 

 

Table 2:

 

 

 

Thank you!

[OTrieger]

@HillaryLansfield 
You can try using Join tool, joining on P

[HillaryLansfield]

I beleive the issue with that is the values in table 2, do not match up exactly with values in table 1. As a result, i believe i will need some sort of interpolation. 

[OTrieger]

@HillaryLansfield 
Try to round up the values to 1 decimal in both files

[HillaryLansfield]

I guess i provided a poor example. These are just mock numbers to illustrate the issue. There will be times when the values (even when rounded to a decimal) will not match. Ive updated the table to show this now.

[OTrieger]

If we are looking at rows 15 to 19, what will be the logic to depreciate them from each other?

[HillaryLansfield]

There isn't exactly logic. This represents a hydropower generator efficiency curve which is generated using real life testing. So based on our testing, if we operate between 1308 to 13.78MW, we will be at the same efficiency.

[alexnajm]

@HillaryLansfield, without logic as @OTrieger is asking for, it will be difficult to help further!

[HillaryLansfield]

Is there no way to interpolate using the data provided?

I am trying to replace an excel which I currently use to complete this task. When using excel, i use this:

=@LinearInterp(P (MW), look up table P (MW), look up table eff %)

this gives me the eff% with the associated P (MW) from table 2. Can this not be replicated in Alteryx? 

[alexnajm]

There is, but you didn't give us this information until now and said "there isn't exactly logic" which is why we needed clarity. If you also provide what the result should be based on your current process, we may be able to replicate on our end. Workflows are also always preferred so we can test things out.

Otherwise my suggestion would be to either use the Linear Regression Tool since it'll likely be most similar to your function, or you can brute force it with Generate Rows to get all values in this range, Formula to calculate the corresponding value, and Join to match it up against your test set.