The object returned by from_source

import earthkit.data as ekd

from_source returns a data object. This object provides some basic information about the data but its primary goal is to convert it to a given representation for further work. The actual data loading is deferred as much as possible, until the data is converted into a given type.

File sources

d = ekd.from_source("file", "test.grib")
d

GRIB file

---

path	test.grib
size	720
types	fieldlist, pandas, xarray, numpy, array

The “available types” tells us the types we can comvert the data into. This list is also available as a property on the data object.

d.available_types

['fieldlist', 'pandas', 'xarray', 'numpy', 'array']

To convert the data we need to call one of the “to_” methods. E.g we can convert our data into a fieldlist.

fl = d.to_fieldlist()
fl.ls()

	parameter.variable	time.valid_datetime	time.base_datetime	time.step	vertical.level	vertical.level_type	ensemble.member	geography.grid_type
0	2t	2020-05-13 12:00:00	2020-05-13 12:00:00	0 days	0	surface	0	regular_ll
1	msl	2020-05-13 12:00:00	2020-05-13 12:00:00	0 days	0	surface	0	regular_ll

Some conversions may involve other conversions under the hood. For example, when GRIB is converted to Xarray, first it is always loaded into a fieldlist then converted to Xarray.

# this first loads the GRIB data into a fieldlist and converts that into Xarray
ds = d.to_xarray()
ds

<xarray.Dataset> Size: 2kB
Dimensions:    (latitude: 8, longitude: 13)
Coordinates:
  * latitude   (latitude) float64 64B 70.0 65.0 60.0 55.0 50.0 45.0 40.0 35.0
  * longitude  (longitude) float64 104B -20.0 -15.0 -10.0 ... 30.0 35.0 40.0
Data variables:
    2t         (latitude, longitude) float64 832B ...
    msl        (latitude, longitude) float64 832B ...
Attributes:
    Conventions:  CF-1.8
    institution:  ECMWF

xarray.Dataset

• Dimensions:
  • latitude: 8
  • longitude: 13
• Coordinates: (2)
  • latitude
    (latitude)
    float64
    70.0 65.0 60.0 ... 45.0 40.0 35.0

    units :

    degrees_north

    standard_name :

    latitude

    long_name :

    latitude

    array([70., 65., 60., 55., 50., 45., 40., 35.])

  • longitude
    (longitude)
    float64
    -20.0 -15.0 -10.0 ... 35.0 40.0

    units :

    degrees_east

    standard_name :

    longitude

    long_name :

    longitude

    array([-20., -15., -10.,  -5.,   0.,   5.,  10.,  15.,  20.,  25.,  30.,  35.,
            40.])

• Data variables: (2)
  • 2t
    (latitude, longitude)
    float64
    ...

    standard_name :

    unknown

    long_name :

    2 metre temperature

    units :

    kelvin

    level_type :

    surface

    _earthkit :

    {'message': b'GRIB\x00\x00l\x01\x00\x004\x80b\x96\xff\x80\xa7\x01\x00\x00\x14\x05\r\x0c\x00\x01\x00\x00\x00\x00\x00\x00\x15\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x01\x02\x04\x010001\x00\x00\x00\x00\x00 \x00\xff\x00\x00\r\x00\x08\x01\x11p\x80N \x80\x00\x88\xb8\x00\x9c@\x13\x88\x13\x88\x00\x00\x00\x00\x00\x00\x00\x0c\x00\x80\x02D\xb9}n\x00\x007777', 'bitsPerValue': 16, 'grid_spec': '{"area": [70, -20, 35, 40], "grid": [5, 5]}'}

    [104 values with dtype=float64]

  • msl
    (latitude, longitude)
    float64
    ...

    standard_name :

    air_pressure_at_mean_sea_level

    long_name :

    Mean sea level pressure

    units :

    pascal

    level_type :

    surface

    _earthkit :

    {'message': b'GRIB\x00\x00l\x01\x00\x004\x80b\x96\xff\x80\x97\x01\x00\x00\x14\x05\r\x0c\x00\x01\x00\x00\x00\x00\x00\x00\x15\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x01\x02\x04\x010001\x00\x00\x00\x00\x00 \x00\xff\x00\x00\r\x00\x08\x01\x11p\x80N \x80\x00\x88\xb8\x00\x9c@\x13\x88\x13\x88\x00\x00\x00\x00\x00\x00\x00\x0c\x00\x80\x02D\xb9}n\x00\x007777', 'bitsPerValue': 16, 'grid_spec': '{"area": [70, -20, 35, 40], "grid": [5, 5]}'}

    [104 values with dtype=float64]

• Attributes: (2)

  Conventions :

  CF-1.8

  institution :

  ECMWF