how to implement lookup tables?

[xolstis]

Hi there, am rather new to labview. Have been looking high and low for some kind of look-up table function that I might be able to implement in labview unsuccessfully.

I need to be able to have a 2D table that gives out a single output taken from the table for a given set of two input variables. Anway to do this easily?

Cheers

[Götz Becker]

Are the two inputs the indices for that 2D Array?

Then a simple "Index Array" is what you need. The function expands the index inputs depending on the dimension of the wired array input.

But i guess i didn

[Mike Ashe]

Hi there, am rather new to labview. Have been looking high and low for some kind of look-up table function that I might be able to implement in labview unsuccessfully.

I need to be able to have a 2D table that gives out a single output taken from the table for a given set of two input variables. Anway to do this easily?

Cheers

Go to NI.com and in DevZone search for Parse Lookup Table

or try here: Parse Lookup Table

Cheers :beer:

[Neville D]

Hi there, am rather new to labview. Have been looking high and low for some kind of look-up table function that I might be able to implement in labview unsuccessfully.

I need to be able to have a 2D table that gives out a single output taken from the table for a given set of two input variables. Anway to do this easily?

Cheers

Hi,

Here is an implementation of a lookup table. The LUT can be either:

- a 2d array of X-col, Y-col,

OR

- a 1d array of (X,Y) clusters.

Given an X, it will interpolate a Y value. Note that the LUT must be monotonically increasing for the LV function to work!

You can add additional logic to check for out of range X values, error generation, interpolating Y given X etc. as needed.

Cheers,

Neville.

Download File:post-2680-1134673935.vi

[xolstis]

Are the two inputs the indices for that 2D Array?

Then a simple "Index Array" is what you need. The function expands the index inputs depending on the dimension of the wired array input.

But i guess i didn

[xolstis]

Hi,

Here is an implementation of a lookup table. The LUT can be either:

- a 2d array of X-col, Y-col,

OR

- a 1d array of (X,Y) clusters.

Given an X, it will interpolate a Y value. Note that the LUT must be monotonically increasing for the LV function to work!

You can add additional logic to check for out of range X values, error generation, interpolating Y given X etc. as needed.

Cheers,

Neville.

Hi Neville,

Have looked at the vi you attached. Correct me if I am wrong but it appears that this vi does something like curve fitting. As in given a graphical function (or in this case by interpolating a series of points on an array), the function returns a value of y for an input of x. Not too diff from say if you had a graph of y = 2x this function simply tells you what y is for a given value of x except in this case no graphical function is given but rather a 1D array is used.

If I am correct in my conclusion this isn't quite what I need because the values I have to fit into the table will probably not fit into any function or curve. Have attached a picture to illustrate what I am trying to do. It sounds really simple but I can't seem to find a simple solution for it.... I am sure there is one and its just eluding me. The parse lookup table suggestion by Michael looks a little complicated am trying to look thru it now to see if it does what I require.

Thanks for the help.

[xolstis]

OK I finally found it was just an index function after all just like the first reply said sorry for the fuss ..... lol.

[Mike Ashe]

The parse lookup table suggestion by Michael looks a little complicated am trying to look thru it now to see if it does what I require.

Apply Occam's Razor: Always choose the simplist possible explaination or solution first. :headbang: