def n2eap(nVectors, flip=True): """ unit vectors to equal-area projection """ nVecs = copy.deepcopy(nVectors) nPnts = nVectors.shape[1] retval = getMem((2,nPnts)) belowEquator = num.where(nVecs[2,:] < -1e-4) if flip: nVecs[:,belowEquator] = -nVecs[:,belowEquator] else: 'put on the equator' nVecs[2,belowEquator] = 0. # num.apply_along_axis(num.linalg.norm, 0, nVecs[0:2,belowEquator]) norms = num.sqrt( nVecs[0,belowEquator]*nVecs[0,belowEquator] + nVecs[1,belowEquator]*nVecs[1,belowEquator] ) nVecs[0:2,belowEquator] = nVecs[0:2,belowEquator] / norms r2 = nVecs[0,:]*nVecs[0,:] + nVecs[1,:]*nVecs[1,:] r2pos = num.where(r2 > 0.) n31 = 1.0 - num.abs(nVecs[2,:]) den = num.ones(nPnts) den[r2pos] = num.sqrt(2.0*r2[r2pos]) dist_np = num.zeros(nPnts) dist_np = num.sqrt(r2 + n31*n31) / den retval = num.vstack((nVecs[0,:] * dist_np, nVecs[1,:] * dist_np)) # .T return retval
def n2sph(nVectors): assert nVectors.shape[0] == 3, 'shape[0] not 3' sph = arrayUtil.getMem((2,nVectors.shape[1])) for iVector in range(nVectors.shape[1]): x = nVectors[0,iVector] y = nVectors[1,iVector] z = nVectors[2,iVector] r = sqrt(x*x+y*y) sph[0,iVector] = atan2(r,z) sph[1,iVector] = atan2(y,x) return sph
def sph2n(coords_sph): '''convert from chi/eta spherical coordinates to normal vectors; can use with coords from femODF.FemHemisphere ''' assert coords_sph.shape[0] == 2, 'shape[0] not 2' z = num.cos(coords_sph[0,:]) rho = num.sin(coords_sph[0,:]) x = rho * num.cos(coords_sph[1,:]) y = rho * num.sin(coords_sph[1,:]) # nVectors = arrayUtil.toArray(num.vstack((x,y,z))) nVectors = getMem((3,coords_sph.shape[1])) nVectors[0,:] = x nVectors[1,:] = y nVectors[2,:] = z return nVectors