def shiftgrid(lon0,datain,lonsin,start=True,cyclic=360.0):
"""
Shift global lat/lon grid east or west.
.. tabularcolumns:: |l|L|
============== ====================================================
Arguments Description
============== ====================================================
lon0 starting longitude for shifted grid
(ending longitude if start=False). lon0 must be on
input grid (within the range of lonsin).
datain original data with longitude the right-most
dimension.
lonsin original longitudes.
============== ====================================================
.. tabularcolumns:: |l|L|
============== ====================================================
Keywords Description
============== ====================================================
start if True, lon0 represents the starting longitude
of the new grid. if False, lon0 is the ending
longitude. Default True.
cyclic width of periodic domain (default 360)
============== ====================================================
returns ``dataout,lonsout`` (data and longitudes on shifted grid).
"""
if np.fabs(lonsin[-1]-lonsin[0]-cyclic) > 1.e-4:
# Use all data instead of raise ValueError, 'cyclic point not included'
start_idx = 0
else:
# If cyclic, remove the duplicate point
start_idx = 1
if lon0 < lonsin[0] or lon0 > lonsin[-1]:
raise ValueError('lon0 outside of range of lonsin')
i0 = np.argmin(np.fabs(lonsin-lon0))
i0_shift = len(lonsin)-i0
if ma.isMA(datain):
dataout = ma.zeros(datain.shape,datain.dtype)
else:
dataout = np.zeros(datain.shape,datain.dtype)
if ma.isMA(lonsin):
lonsout = ma.zeros(lonsin.shape,lonsin.dtype)
else:
lonsout = np.zeros(lonsin.shape,lonsin.dtype)
if start:
lonsout[0:i0_shift] = lonsin[i0:]
else:
lonsout[0:i0_shift] = lonsin[i0:]-cyclic
dataout[...,0:i0_shift] = datain[...,i0:]
if start:
lonsout[i0_shift:] = lonsin[start_idx:i0+start_idx]+cyclic
else:
lonsout[i0_shift:] = lonsin[start_idx:i0+start_idx]
dataout[...,i0_shift:] = datain[...,start_idx:i0+start_idx]
return dataout,lonsout
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