xy graph to boolean array

[altenbach]

Yes, array indices are quantized to integers. You cannot have an element at index 1.5, for example.

It is a simple linear transformation between values and indices. Typically, that involves an offset and a spacing. (e.g. if the values range from 1000.0 to 1000.9, you would use an offset of 1000 and a spacing of 0.1. 1000->index=0, 1000.1, index=1, etc.) I have no idea what you mean by decimal places, that typically has no meaning for binary data. Does the instrument have a natural step size, for example?

From the data range and spacing, you can calculate the array size you need. If you make the spacing too fine, you'll have large gaps between points and would need to interpolate in some way to fill the gaps.