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	tPISMNC.py - pism-exp-gsw - ice stream and sediment transport experiments
	git clone git://src.adamsgaard.dk/pism-exp-gsw
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	tPISMNC.py (5381B)
	---
	1 #!/usr/bin/env python3
	2
	3 try:
	4 import netCDF4 as netCDF
	5 except:
	6 print("netCDF4 is not installed!")
	7 sys.exit(1)
	8
	9
	10 class PISMDataset(netCDF.Dataset):
	11
	12 def create_time(self, use_bounds=False, length=None, units=None):
	13 self.createDimension('time', size=length)
	14 t_var = self.createVariable('time', 'f8', ('time',))
	15
	16 t_var.axis = "T"
	17 t_var.long_name = "time"
	18 if not units:
	19 t_var.units = "seconds since 1-1-1" # just a default
	20 else:
	21 t_var.units = units
	22
	23 if use_bounds:
	24 self.createDimension('n_bounds', 2)
	25 self.createVariable("time_bounds", 'f8', ('time', 'n_bounds'…
	26 t_var.bounds = "time_bounds"
	27
	28 def create_dimensions(self, x, y, time_dependent=False, use_time_bou…
	29 """
	30 Create PISM-compatible dimensions in a NetCDF file.
	31 """
	32
	33 if time_dependent and not 'time' in list(self.variables.keys()):
	34 self.create_time(use_time_bounds)
	35
	36 self.createDimension('x', x.size)
	37 self.createDimension('y', y.size)
	38
	39 x_var = self.createVariable('x', 'f8', ('x',))
	40 x_var[:] = x
	41
	42 y_var = self.createVariable('y', 'f8', ('y',))
	43 y_var[:] = y
	44
	45 x_var.axis = "X"
	46 x_var.long_name = "X-coordinate in Cartesian system"
	47 x_var.units = "m"
	48 x_var.standard_name = "projection_x_coordinate"
	49
	50 y_var.axis = "Y"
	51 y_var.long_name = "Y-coordinate in Cartesian system"
	52 y_var.units = "m"
	53 y_var.standard_name = "projection_y_coordinate"
	54
	55 self.sync()
	56
	57 def append_time(self, value, bounds=None):
	58 if 'time' in list(self.dimensions.keys()):
	59 time = self.variables['time']
	60 N = time.size
	61 time[N] = value
	62
	63 if bounds:
	64 self.variables['time_bounds'][N, :] = bounds
	65
	66 def set_attrs(self, var_name, attrs):
	67 """attrs should be a list of (name, value) tuples."""
	68 if not attrs:
	69 return
	70
	71 for (name, value) in attrs.items():
	72 if name == "_FillValue":
	73 continue
	74 setattr(self.variables[var_name], name, value)
	75
	76 def define_2d_field(self, var_name, time_dependent=False, dims=None,…
	77 """
	78 time_dependent: boolean
	79
	80 dims: an optional list of dimension names. use this to override …
	81 default order ('time', 'y', 'x')
	82
	83 attrs: a dictionary of attributes
	84 """
	85 if not dims:
	86 if time_dependent:
	87 dims = ('time', 'y', 'x')
	88 else:
	89 dims = ('y', 'x')
	90
	91 try:
	92 var = self.variables[var_name]
	93 except:
	94 if attrs is not None and '_FillValue' in list(attrs.keys()):
	95 var = self.createVariable(var_name, nc_type, dims,
	96 fill_value=attrs['_FillValue'])
	97 else:
	98 var = self.createVariable(var_name, nc_type, dims)
	99
	100 self.set_attrs(var_name, attrs)
	101
	102 return var
	103
	104 def define_timeseries(self, var_name, attrs=None):
	105 try:
	106 if attrs is not None and '_FillValue' in list(attrs.keys()):
	107 var = self.createVariable(var_name, 'f8', ('time',),
	108 fill_value=attrs['_FillValue'])
	109 else:
	110 var = self.createVariable(var_name, 'f8', ('time',))
	111 except:
	112 var = self.variables[var_name]
	113
	114 self.set_attrs(var_name, attrs)
	115
	116 return var
	117
	118 def write(self, var_name, data, time_dependent=False, attrs=None):
	119 """
	120 Write time-series or a 2D field to a file.
	121 """
	122
	123 if data.ndim == 1:
	124 return self.write_timeseries(var_name, data, attrs=attrs)
	125 elif data.ndim == 2:
	126 return self.write_2d_field(var_name, data, time_dependent, a…
	127 else:
	128 return None
	129
	130 def write_2d_field(self, var_name, data, time_dependent=False, attrs…
	131 """
	132 Write a 2D numpy array to a file in a format PISM can read.
	133 """
	134
	135 var = self.define_2d_field(var_name, time_dependent, attrs=attrs)
	136
	137 if time_dependent:
	138 last_record = self.variables['time'].size - 1
	139 var[last_record, :, :] = data
	140 else:
	141 var[:] = data
	142
	143 return var
	144
	145 def write_timeseries(self, var_name, data, attrs=None):
	146 """Write a 1D (time-series) array to a file."""
	147
	148 var = self.define_timeseries(var_name, attrs=attrs)
	149 var[:] = data
	150
	151 return var
	152
	153
	154 if __name__ == "__main__":
	155 # produce a NetCDF file for testing
	156 from numpy import linspace, meshgrid
	157
	158 nc = PISMDataset("foo.nc", 'w')
	159
	160 x = linspace(-100, 100, 101)
	161 y = linspace(-100, 100, 201)
	162
	163 xx, yy = meshgrid(x, y)
	164
	165 nc.create_dimensions(x, y, time_dependent=True, use_time_bounds=True)
	166
	167 nc.define_2d_field("xx", time_dependent=True,
	168 attrs={"long_name": "xx",
	169 "comment": "test variable",
	170 "valid_range": (-200.0, 200.0)})
	171
	172 for t in [0, 1, 2, 3]:
	173 nc.append_time(t, (t - 1, t))
	174
	175 nc.write("xx", xx + t, time_dependent=True)
	176 nc.write("yy", yy + 2 * t, time_dependent=True)
	177
	178 nc.close()