function tr_xform=cosmo_fmri_convert_xform(fmt, xform)
% convert xform code between numeric and string in fmri dataset
%
% tr_xform=cosmo_fmri_convert_xform(fmt, xform)
%
% Inputs:
% fmt one of:
% - 'nii' (nifti)
% - 'afni' (afni)
% - 'bv' (BrainVoyager)
% xform either
% - a string, in which it must be one of
% 'scanner_anat','aligned_anat','talairach',
% 'mni_152', 'unknown'
% - a number, in which case it must be the view type for
% nii (sform or qform) or afni (the first elment of
% SCENE_TYPE). Any number in bv corresponds with
% 'unknown'.
%
% Output:
% tr_xform if the input is a string, then the output is the
% corresponding view type (numeric); and vice versa
% if the viewtype cannot be found, the string 'unknown'
% or the corresponding view type is returned
%
% Examples
% % Number to string:
%
% % - NIFTI
% cosmo_fmri_convert_xform('nii',1)
% %|| 'scanner_anat'
% cosmo_fmri_convert_xform('nii',2)
% %|| 'aligned_anat'
% cosmo_fmri_convert_xform('nii',3)
% %|| 'talairach'
% cosmo_fmri_convert_xform('nii',4)
% %|| 'mni_152'
% % any unknown number returns 'scanner_anat'
% cosmo_fmri_convert_xform('nii',0)
% %|| 'scanner_anat'
% cosmo_fmri_convert_xform('nii',NaN)
% %|| 'scanner_anat'
%
% % - AFNI
% cosmo_fmri_convert_xform('afni',0)
% %|| 'scanner_anat'
% cosmo_fmri_convert_xform('afni',1)
% %|| 'aligned_anat'
% cosmo_fmri_convert_xform('afni',2)
% %|| 'talairach'
% % any unknown number returns 'scanner_anat'
% cosmo_fmri_convert_xform('afni',10)
% %|| 'scanner_anat'
% cosmo_fmri_convert_xform('afni',NaN)
% %|| 'scanner_anat'
%
% % - BV
% % any number returns 'talairach'
% cosmo_fmri_convert_xform('bv',0)
% %|| 'talairach'
% cosmo_fmri_convert_xform('bv',NaN)
% %|| 'talairach'
%
% % String to number:
%
% % - NIFTI
% cosmo_fmri_convert_xform('nii','scanner_anat')
% %|| 1
% cosmo_fmri_convert_xform('nii','aligned_anat')
% %|| 2
% cosmo_fmri_convert_xform('nii','talairach')
% %|| 3
% cosmo_fmri_convert_xform('nii','mni_152')
% %|| 4
% cosmo_fmri_convert_xform('nii','unknown')
% %|| 1
%
% % - AFNI
% cosmo_fmri_convert_xform('afni','scanner_anat')
% %|| 0
% cosmo_fmri_convert_xform('afni','aligned_anat')
% %|| 1
% cosmo_fmri_convert_xform('afni','talairach')
% %|| 2
% % treat as talairach
% cosmo_fmri_convert_xform('afni','mni_152')
% %|| 2
% % unkown
% cosmo_fmri_convert_xform('afni','unknown')
% %|| 0
%
% % - BV
% % all are unknown in BV, because BV does not support this
% cosmo_fmri_convert_xform('bv','scanner_anat')
% %|| 0
% cosmo_fmri_convert_xform('bv','aligned_anat')
% %|| 0
% cosmo_fmri_convert_xform('bv','talairach')
% %|| 0
% cosmo_fmri_convert_xform('bv','mni_152')
% %|| 0
% cosmo_fmri_convert_xform('bv','unknown')
% %|| 0
%
% % any other input gives an error
% cosmo_fmri_convert_xform('unknown','talairach')
% %|| error('unsupported format ''unknown''')
% cosmo_fmri_convert_xform('unknown',1)
% %|| error('unsupported format ''unknown''')
%
% # For CoSMoMVPA's copyright information and license terms, #
% # see the COPYING file distributed with CoSMoMVPA. #
