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Merged
bblay merged 2 commits into from
Aug 1, 2013
Merged

Switch to using DimCoord.from_regular #642

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cc8bf61
Switch to using DimCoord.from_regular
rhattersley Jul 24, 2013
1872690
Use DimCoord.__new__ to construct object
rhattersley Jul 30, 2013
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51 changes: 51 additions & 0 deletions lib/iris/coords.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1180,6 +1180,57 @@ def from_coord(coord):
coord_system=copy.deepcopy(coord.coord_system),
circular=getattr(coord, 'circular', False))

@classmethod
def from_regular(cls, zeroth, step, count, standard_name=None,
long_name=None, var_name=None, units='1', attributes=None,
coord_system=None, circular=False, with_bounds=False):
"""
Create a :class:`DimCoord` with regularly spaced points, and
optionally bounds.

The majority of the arguments are defined as for
:meth:`Coord.__init__`, but those which differ are defined below.

Args:

* zeroth:
The value *prior* to the first point value.
* step:
The numeric difference between successive point values.
* count:
The number of point values.

Kwargs:

* with_bounds:
If True, the resulting DimCoord will possess bound values
which are equally spaced around the points. Otherwise no
bounds values will be defined. Defaults to False.

"""
coord = DimCoord.__new__(cls)
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@bblay bblay Jul 30, 2013

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@esc24's cls.__new__(cls) is better because it works for subclasses too.
We want SparklyDimCoord.from_regular to return a SparklyDimCoord.

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@rhattersley rhattersley Jul 30, 2013

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Except we have no idea what arguments the SparklyDimCoord constructor needs. NB. If SparklyDimCoord wants to override from_regular it still can.

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@rhattersley rhattersley Jul 30, 2013

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NB. DimCoord.__new__(cls) will return an instance of SparklyDimCoord ... that's what the cls parameter is for.

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@esc24 esc24 Jul 31, 2013

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@rhattersley is too polite to point out I was talking nonsense with cls.__new__(cls) 😞

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@bblay bblay Jul 31, 2013

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NB. DimCoord.new(cls) will return an instance of SparklyDimCoord ... that's what the cls parameter is for.

Great, no problem then.

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@bblay bblay Jul 31, 2013

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@rhattersley is too polite to point out I was talking nonsense

@esc24 is too polite to point out that's "we", not "I" 😀


coord.standard_name = standard_name
coord.long_name = long_name
coord.var_name = var_name
coord.units = units
coord.attributes = attributes
coord.coord_system = coord_system
coord.circular = circular
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@pelson pelson Jul 30, 2013

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Do you know of any smart way of keeping the attribute definitions in sync? I'm concerned that a new attribute will be added in init which is expected, but is not added by this method.

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@bblay bblay Jul 30, 2013

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If we were calling the constructor, as I queried above, and this new attribute is expected, it'll be an arg and would fail if omitted?

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@rhattersley rhattersley Jul 30, 2013

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Do you know of any smart way of keeping the attribute definitions in sync?

In short ... no. 😒

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@bblay bblay Jul 30, 2013

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Coord._set_metadata ?

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@rhattersley rhattersley Jul 31, 2013

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A method such as Coord._set_metadata doesn't help unless it's also used by Coord.__init__. But then how do we provide docstrings for the instance attributes?

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@bblay bblay Jul 31, 2013

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hmm...
i suppose, because init needs to accept them all and pass them to set_metadata, it's not hard to put them in init, as =None, with docstrings.
i'm not going to push for this but it would help protect these functions from drift.

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@rhattersley rhattersley Jul 31, 2013

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I'll see what the negative performance impact is of setting the values twice...

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@rhattersley rhattersley Jul 31, 2013

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Adding Coord._set_metadata completely negates the performance benefit. 😑

Plus there's still the question of how to handle attributes which are specific to DimCoord (i.e. currently just circular). One can't just override _set_metadata because it's used by Coord.__init__ which has no knowledge of the extra attributes. Anyway ... it's all hypothetical ...there's no point in the PR if there's no benefit 😉


points = (zeroth+step) + step*np.arange(count, dtype=np.float32)
points.flags.writeable = False
coord._points = points

if with_bounds:
bounds = np.concatenate([[points - delta], [points + delta]]).T
bounds.flags.writeable = False
coord._bounds = bounds
else:
coord._bounds = None

return coord

def __init__(self, points, standard_name=None, long_name=None,
var_name=None, units='1', bounds=None, attributes=None,
coord_system=None, circular=False):
Expand Down
14 changes: 12 additions & 2 deletions lib/iris/fileformats/pp.py
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Expand Up @@ -1109,8 +1109,13 @@ def regular_points(self, xy):
Args:

* xy - a string, "x" or "y" to specify the dimension for which to return points.


.. deprecated:: 1.5

"""
msg = "The 'regular_points' method is deprecated."
warnings.warn(msg, UserWarning, stacklevel=2)

if xy.lower() == "x":
bz = self.bzx
bd = self.bdx
Expand All @@ -1130,8 +1135,13 @@ def regular_bounds(self, xy):
Args:

* xy - a string, "x" or "y" to specify the dimension for which to return points.


.. deprecated:: 1.5

"""
msg = "The 'regular_bounds' method is deprecated."
warnings.warn(msg, UserWarning, stacklevel=2)

if xy.lower() == "x":
delta = 0.5 * self.bdx
elif xy.lower() == "y":
Expand Down
15 changes: 9 additions & 6 deletions lib/iris/fileformats/pp_rules.py
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Expand Up @@ -15,6 +15,9 @@
# You should have received a copy of the GNU Lesser General Public License
# along with Iris. If not, see <http://www.gnu.org/licenses/>.

# DO NOT EDIT DIRECTLY
# Auto-generated from SciTools/iris-code-generators:tools/gen_rules.py

import warnings

import numpy as np
Expand Down Expand Up @@ -102,25 +105,25 @@ def convert(cube, f):
(f.bdx != 0.0) and \
(len(f.lbcode) != 5) and \
(f.lbcode[0] == 1):
cube.add_dim_coord(DimCoord(f.regular_points("x"), standard_name=f._x_coord_name(), units='degrees', circular=(f.lbhem in [0, 4]), coord_system=f.coord_system()), 1)
cube.add_dim_coord(DimCoord.from_regular(f.bzx, f.bdx, f.lbnpt, standard_name=f._x_coord_name(), units='degrees', circular=(f.lbhem in [0, 4]), coord_system=f.coord_system()), 1)

if \
(f.bdx != 0.0) and \
(len(f.lbcode) != 5) and \
(f.lbcode[0] == 2):
cube.add_dim_coord(DimCoord(f.regular_points("x"), standard_name=f._x_coord_name(), units='degrees', circular=(f.lbhem in [0, 4]), coord_system=f.coord_system(), bounds=f.regular_bounds("x")), 1)
cube.add_dim_coord(DimCoord.from_regular(f.bzx, f.bdx, f.lbnpt, standard_name=f._x_coord_name(), units='degrees', circular=(f.lbhem in [0, 4]), coord_system=f.coord_system(), with_bounds=True), 1)

if \
(f.bdy != 0.0) and \
(len(f.lbcode) != 5) and \
(f.lbcode[0] == 1):
cube.add_dim_coord(DimCoord(f.regular_points("y"), standard_name=f._y_coord_name(), units='degrees', coord_system=f.coord_system()), 0)
cube.add_dim_coord(DimCoord.from_regular(f.bzy, f.bdy, f.lbrow, standard_name=f._y_coord_name(), units='degrees', coord_system=f.coord_system()), 0)

if \
(f.bdy != 0.0) and \
(len(f.lbcode) != 5) and \
(f.lbcode[0] == 2):
cube.add_dim_coord(DimCoord(f.regular_points("y"), standard_name=f._y_coord_name(), units='degrees', coord_system=f.coord_system(), bounds=f.regular_bounds("y")), 0)
cube.add_dim_coord(DimCoord.from_regular(f.bzy, f.bdy, f.lbrow, standard_name=f._y_coord_name(), units='degrees', coord_system=f.coord_system(), with_bounds=True), 0)

if \
(f.bdy == 0.0) and \
Expand All @@ -142,7 +145,7 @@ def convert(cube, f):
(len(f.lbcode) == 5) and \
(f.lbcode.ix == 10) and \
(f.bdx != 0):
cube.add_dim_coord(DimCoord(f.regular_points("x"), standard_name=f._y_coord_name(), units='degrees', coord_system=f.coord_system()), 1)
cube.add_dim_coord(DimCoord.from_regular(f.bzx, f.bdx, f.lbnpt, standard_name=f._y_coord_name(), units='degrees', coord_system=f.coord_system()), 1)

if \
(len(f.lbcode) == 5) and \
Expand Down Expand Up @@ -173,7 +176,7 @@ def convert(cube, f):
(f.lbcode[-1] == 1) and \
(f.lbcode.ix == 13) and \
(f.bdx != 0):
cube.add_dim_coord(DimCoord(f.regular_points("x"), long_name='site_number', units='1'), 1)
cube.add_dim_coord(DimCoord.from_regular(f.bzx, f.bdx, f.lbnpt, long_name='site_number', units='1'), 1)

if \
(len(f.lbcode) == 5) and \
Expand Down