Filtering and Editing contents of a 2D array

[Ackalap]

Hello I'm using Labview 2020 to collect data from an STS Ocean Insight Spectrometer and I could use some help applying some filters to the result spectra. The spectrometer outputs two arrays, one for the wavelengths detected and one for the intensity of those wavelengths, these I can then bundle and display on an XY Graph.

There are two things I would like to be able to do:

• Set a minimum intensity threshold for detected wavelengths, if the intensity is below that threshold it will be set to 0, otherwise it will be displayed as is.
• Have the option to only show a specific range of wavelengths. Eg. 300nm < X < 500nm would be displayed while all others would be set to 0.

I know how to write these parameters in C++ but I don't know how I would apply it to Labview. In C++ it would look something like this:

int i;
int min_wave, max_wave, min_int; //Wavelength Ranges and Intensity Threshold

double i_int[1025]; //Array with initial intensity values
double f_int[1025]; //Array with final intensity values
double wavelengths[1025]; //Array with detected wavelengths

int main
{
	for (i = 0; i < 1025; i++) //Loop through wavelength and intensity arrays, these have a max size of 1025 elements
	{
		if (i_int[i] < min_int || wavelengths[i] < min_wave || wavelengths[i] > max_wave) //If intensity is less than min. intensity or wavelength is outside the range of wavelengths chosen, intensity is set to 0
		{
			f_int[i] = 0;
		}

		else //Keep intesnity value if it passes both filters
		{
			f_int[i] = i_int[i];
		}

	}
}

I would like to put it into the formula node in the vi I attached but I'm not familiar enough with the syntax for it. Also if it's easier to do without a formula node I'd welcome any suggestion with regards to that too. 

[FireFist-Redhawk · Accepted solution]

This is all you need:

In general, it's better practice to simply not graph points you don't want to see, rather than set their y value to 0. So that's how I coded it, take the full set of data and filter out any data that is 1) outside the wavelength limits, and 2) beneath the minimum intensity threshold.

[GerdW]

Hi,

---

@FireFist-Redhawk wrote:

In general, it's better practice to simply not graph points you don't want to see, rather than set their y value to 0.

---

Replace those "don't want to see" points by NaN (instead of zero)!

[Ackalap]

Hi thanks for the reply, I understand your what you're saying about not plotting the points I want ignored and normally thats what I would do. But since this is a graph of a spectrum of light I would prefer to zero the unwanted signals as opposed to not plotting them, both from a practical sense as well as an aesthetic one. I won't lie, I find the zeroed out graph much nicer to look at than the one with most of the points missing.

OriginalPoints not PlottedReplaced with 0