export to iode

[gdementen]

Here is the current code we use.

# la_iode.py
# ----------
# Interface between larray objects and IODE ws

from larray import *
import iode

def larray_to_ws(array, time='time', vars='vars'):
    '''Replace the IODE variables in memory by the array contents

    Parameters
    ----------
    array : LArray
        array with (exactly) 2 axes
        - vars = IODE variable names
        - time = time labels (yearly : 1990 1991...)
    time : str, int or Axis
        axis to use for the time.
    vars : str, int or Axis
        axis to use for the variables.

    Examples
    --------
    Load an array from a .var file, modify its content and save it back to a
    .var file.

    >>> # Load an IODE .var file in an larray object [vars, time]
    >>> surv = iode.wsloadvarpy("v00Mcj.var")
    >>> surv.info
    TODO
    >>> # Modify some variables in the array
    >>> surv['VF00'] = -0.123
    >>> # Replace the IODE variable WS in memory by the larray contents
    >>> larray_to_ws(surv)
    >>> # Save the IODE ws in a .var file
    >>> iode.wssavevar("toto.var")

    Create an array from scratch and save it to a .var file.

    >>> # Create an larray object (with axes vars and time)
    >>> arr = ndrange('vars=X,Y;time=2000..2005')
    >>> # Copy array into IODE memory
    >>> larray_to_ws(arr)
    >>> # Save the iode memory contents in a .var file
    >>> iode.wssavevar("la.var")
    '''
    def iodeline(line):
        "Execute a single IODE report line instruction."

        rc = iode.reportline(line)
        if rc != 0:
            # GDM> 
            # * ideally this should be done in iode.reportline directly
            # * ideally, we should raise different exceptions based on rc
            raise Exception('report line failed to execute (code {}):\n{}'
                            .format(rc, line))
    assert isinstance(array, LArray)
    time = array.axes[time]
    vars = array.axes[vars]
    # converting to int to avoid .0 for float labels
    smplfrom = str(int(time.i[0])) + 'Y1 '  # <-- GDM: is the space necessary?
    smplto   = str(int(time.i[-1])) + 'Y1'

    iodeline("$WsClearVar")
    iodeline("$WsSample {} {}".format(smplfrom, smplto))

    # loop on vars
    # GDM> It would be better if we could pass data directly by value
    for name in vars:
        cmd_parts = ['$DataUpdateVar {} {}'.format(name, smplfrom)]
        cmd_parts += [repr(array[name, t]) for t in time]
        cmd = ' '.join(cmd_parts)
        iodeline(cmd)

TODO:

• combine_axes if more than 2 axes
• include iode.wssavevar(path)

[gdementen]

more TODO:

• remove "vars" argument (use all non "time" axes combined)

potential TODO:

• output several variables in one shot (ie implicit stack them)???

Usage would be:

>>> arrays_to_iode((arr1, arr2), 'output.var')
>>> arrays_to_iode({'array1': arr1, 'array2': arr2}, 'output.var')
>>> # maybe requiring an explicit stack is better (or only when renaming variables?)
>>> arrays_to_iode(stack(array1=arr1, array2=arr2), 'output.var')
>>> arrays_to_iode('output.var', array1=arr1, array2=arr2)

Older syntaxes we should not implement:

>>> arrays_to_iode((arr1, arr2), 'output.var', names=('array1', 'array2'))
>>> # arrays_to_iode([('array1', arr1), ('array2', arr2)], 'output.var')
>>> arrays_to_iode(stack([('array1', arr1), ('array2', arr2)]), 'output.var') # <-- not a good syntax

Some preliminary code:

def arrays_to_iode(variables, path, names=None, time='time', sep='_')
    if names is None:
        names = [get_name(v) for v in variables]
    stacked = stack(list(zip(names, variables)), 'variables')
    combined = ...
    combined_axis = ...
    for name in combined_axis:
        ...