docs: some parts in documentation are incorrect. #352

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1. ycexiao commented on Jul 24, 2025

   

   ycexiao

   on Jul 24, 2025

   ContributorAuthor

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   The function DiffractionObject.get_array_index

       def get_array_index(self, xtype, xvalue):
           """Return the index of the closest value in the array associated with
           the specified xtype and the value provided.
           ...
           xtype = self._input_xtype
           xarray = self.on_xtype(xtype)[0]
           if len(xarray) == 0:
               raise ValueError(
                   f"The '{xtype}' array is empty. "
                   "Please ensure it is initialized."
               )
           index = (np.abs(xarray - xvalue)).argmin()
           return index
           """
   

   So the input parameterxtype doesn't have an effect at all. Thus, the following code

   x = np.linspace(0, 90, 1000)
   y = np.random.rand(1000)
   tmp = DiffractionObject(
        xarray=x,
        yarray=y,
        xtype="angle",
        wavelength=1.54,
   )
   index_angle = tmp.get_array_index(xvalue=0.24, xtype="angle")
   index_q_from_function = tmp.get_array_index(xvalue=0.24, xtype="q")
   real_index_q =  np.argmin(np.abs(tmp.on_xtype("q")[0] - 0.24))
   print(index_angle == index_q_from_function)
   print(index_q_from_function == real_index_q)
   

   returns True and False.

   @sbillinge, is it a bug we want to fix?
2. ycexiao

   changed the title [-]docs: example of using `get_array_index` failed[/-] [+]docs: Some parts in documentation are incorrect.[/+] on Jul 24, 2025
3. ycexiao

   changed the title [-]docs: Some parts in documentation are incorrect.[/-] [+]docs: some parts in documentation are incorrect.[/+] on Jul 24, 2025
4. sbillinge commented on Jul 25, 2025

   

   sbillinge

   on Jul 25, 2025

   Contributor

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   @sbillinge, is it a bug we want to fix?

   yes, this looks like a bug. The intent is that the user wants the index of, for example, Q=23.4 a-1, or tth=45 deg. so inside we want to use the relevant xarray, be it Q or tth or whatever.

   Let's write some tests for this then fix the code.

   Please check everywhere in the code where this is used, and also the docs so everything agrees. Maybe do all that work on separate PR clsing a separate issue.

   Please also fix all the other documentation issues that you found.

   👍React with 👍1Reacted by Yuchen Xiao
5. sbillinge

   closed this as completedin #357on Jul 25, 2025