Source code for pycif.plugins.datastreams.fields.netcdf_cams.fetch

import os
import numpy as np
import pandas as pd
import datetime
from netCDF4 import Dataset
from logging import debug
from .....utils import path




def fetch(ref_dir, ref_file, input_interval, target_dir, tracer=None,
          component=None):
    """
    Reads netcdf files from CAMS for a given species.
    One file per month.

    Args
    -----

    - ref_dir: directory where the original files are found
    - ref_file: (template) name of the original files
    - input_interval: list of two dates: the beginning and end of the simulation
    - target_dir: directory where the links to the orginal files are created

    Returns
    ---------
    - list_dates
    - list_files

    """

    # Force the dates to include full months
    datei, datef = input_interval
    datei = datetime.datetime(year=datei.year, month=datei.month, day=1)
    datef = datetime.datetime(year=datef.year, month=datef.month, day=1)
    datef = datef +  \
        datetime.timedelta(
            days=int(pd.DatetimeIndex([datef]).days_in_month[0]))
    list_period_dates = \
        pd.date_range(datei, datef, freq=tracer.file_freq, inclusive="left")

    list_files = {}
    list_dates = {}
    for dd in list_period_dates:
        file = dd.strftime("{}/{}".format(ref_dir, ref_file))
        debug(f"Reading CAMS data for {dd} in file {file}")

        # Fetch date frequency
        with Dataset(file, "r") as f:
            ntimes = f.dimensions["time"].size

        # to_timedelta does not work with all frequencies!
        datef = dd +  \
            datetime.timedelta(
                days=int(pd.DatetimeIndex([dd]).days_in_month[0]))

        list_hours = pd.date_range(dd, datef, periods=ntimes + 1)
        list_dates[dd] = [[hh0, hh1]
                          for hh0, hh1 in zip(list_hours[:-1], list_hours[1:])]
        list_files[dd] = (len(list_hours) * [file])

        target_file = "{}/{}".format(target_dir, os.path.basename(file))
        path.link(file, target_file)

    return list_files, list_dates