Creating an array to use as graph indeces.

[seanMeredith]

Hello all. 

I am sure this is probably a very basic question.

I am getting an array of length 1340- each value represents an intensity at a given pixel. Each pixel represents a wavelength in a y = mx + b form. So I initially had no problem using an intensity graph and setting the offset and multiplier within the graph's settings.

Now, however, I want to calculate the raman shift, which is more involved than the linear fit before:

I need to: create an array from 1 to 1340

Apply the y = mx + b to go from pixel length to wavelength

apply the above transformation (where lambda_ex is a constant) to each value.

Use these as an x axis to graph against my already acquired y-axis data.

Does anyone have any tips?

I did this but this results in an indicator array that I am not really able to further manipulate... Sorry, I am a noob to Labview

[jjohn1]

You do not need to scale the axes.

Use the LabVIEW Help -->Find Examples... drop down menu to open the LabVIEW Example Finder and search for the "XY Graph Data Types.vi" VI.  It shows multiple ways to graph XY data.

[GerdW]

Hi sean,

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@seanMeredith wrote:

I need to: create an array from 1 to 1340

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This loop will NOT create the desired array of 1…1340 as "i" starts with 0 and will have the value 1339 in the last iteration…

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@seanMeredith wrote:

Apply the y = mx + b to go from pixel length to wavelength

I did this but this results in an indicator array that I am not really able to further manipulate... Sorry, I am a noob to Labview

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Why don't you use basic math operations (like multiply and add) on your array? (Ever heard of "polymorphism" with respect to LabVIEW?)

What is "pixel length"?

[altenbach]

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@seanMeredith wrote:

Hello all. 

I am sure this is probably a very basic question.

I am getting an array of length 1340- each value represents an intensity at a given pixel. Each pixel represents a wavelength in a y = mx + b form. So I initially had no problem using an intensity graph and setting the offset and multiplier within the graph's settings.

Now, however, I want to calculate the raman shift, which is more involved than the linear fit before:

I need to: create an array from 1 to 1340

Apply the y = mx + b to go from pixel length to wavelength

apply the above transformation (where lambda_ex is a constant) to each value.

Use these as an x axis to graph against my already acquired y-axis data.

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You seem to have a mix of several ambiguous problem and I cannot make sense of what you are saying.

• An intensity graph is for data with two independent axis (e.g. a 2D array where the indices relate to X and Y and the value is Z.)
• You talk about an array of length 1340, which is 1D and just requires a plain graph.
• Pixels are in 2D units, so what is a "pixel" in your world?
• Once you transform, the axis is no longer linear in lambda.
• Maybe you could graph a suitable transform?
• Maybe you could do a linear ramp of Raman shifts and remap by interpolating into your existing data

Please attach a simple example containing typical data. Everybody here know how a FOR loop looks like, no need to attach silly pictures.