Installation and first usage¶

1. Installation¶

Note

For VRE (Virtual Research Environment) users (it’s free! - read more):

viresclient is already installed so skip this step. Log in at https://vre.vires.services/ and refer to documentation at https://swarm-vre.readthedocs.io/. The access token should be automatically configured so you can jump in with the notebook demos.

Python ≥ 3.5 is required. Tested primarily on Linux, but macOS and Windows should also work (on v0.4+).

It can currently be installed with:

pip install viresclient

Dependencies:

requests
Jinja2
tables
tqdm
cdflib
pandas
xarray

pip will fetch these automatically - if you are using conda, it may be better to install these first using conda instead:

conda install requests jinja2 pytables tqdm pandas xarray
pip install viresclient

Recommended setup if starting without Python already¶

Install Miniconda: https://docs.conda.io/en/latest/miniconda.html

Create a new conda environment with some recommended packages:

conda create --name py37 scipy matplotlib pandas xarray cartopy jupyter jupyterlab flake8 dask h5py netCDF4 jinja2 pytables tqdm

Activate the new environment (you do this each time you want to use it):
conda activate py37

Use pip to install viresclient:
```
pip install viresclient
```

2. First usage / Configuration¶

Note

For Jupyter notebook users:

On creation of a SwarmRequest object, you will automatically be prompted to set a token. Just try:

from viresclient import SwarmRequest
request = SwarmRequest()

and follow the instructions.

A first usage guide is provided as a Jupyter notebook (view). To run the notebook on your computer running Jupyter locally, right click here to download, or use git to get the whole example repository:

git clone https://github.com/Swarm-DISC/Swarm_notebooks.git

Access to the service is through the same user account as on the web interface (https://vires.services/) and is enabled through an access token (essentially a password). To get a token, log in to the website and click on your name on the top right to access the settings (or follow this link). From here, click on “Manage access tokens” and follow the instructions to create a new token.

To set your token in the client, use either the Python interface:

from viresclient import set_token
set_token("https://vires.services/ows")
# (you will now be prompted to enter the token)

or the command line tool:

$ viresclient set_token https://vires.services/ows
Enter access token: r-8-mlkP_RBx4mDv0di5Bzt3UZ52NGg-

$ viresclient set_default_server https://vires.services/ows

See also: see Configuration Details and Access Token Management

3. Example use¶

Note

A brief introduction is given here. For more possibilities, see Introduction to notebooks

Choose which collection to access (see Available parameters for Swarm data for more options):

import datetime as dt
from viresclient import SwarmRequest

request = SwarmRequest()
request.set_collection("SW_OPER_MAGA_LR_1B")

Next, use .set_products() to choose a combination of variables to retrieve, specified by keywords.

measurements are measured by the satellite and members of the specified collection
models are evaluated on the server at the positions of the satellite
auxiliaries are additional parameters not unique to the collection
if residuals is set to True then only data-model residuals are returned
optionally use sampling_step to specify a resampling of the original time series (an ISO-8601 duration).

request.set_products(measurements=["F","B_NEC"],
                     models=["MCO_SHA_2C", "MMA_SHA_2C-Primary", "MMA_SHA_2C-Secondary"],
                     auxiliaries=["QDLat", "QDLon", "MLT", "OrbitNumber", "SunZenithAngle"],
                     residuals=False,
                     sampling_step="PT10S")

Set a parameter range filter to apply. You can add multiple filters in sequence

request.set_range_filter(parameter="Latitude",
                         minimum=0,
                         maximum=90)

request.set_range_filter("Longitude", 0, 90)

Specify the time range from which to retrieve data, make the request to the server:

data = request.get_between(start_time=dt.datetime(2016,1,1),
                           end_time=dt.datetime(2016,1,2))

Transfer your data to a pandas.DataFrame, or a xarray.Dataset, or just save it as is:

df = data.as_dataframe()
ds = data.as_xarray()
data.to_file('outfile.cdf', overwrite=False)

The returned data has columns for:

Spacecraft, Timestamp, Latitude, Longitude, Radius

those specified by measurements and auxiliaries

… and model values and residuals, named as:

F_<model_id> – scalar field

B_NEC_<model_id> – vector field

F_res_<model_id> – scalar field residual (F - F_<model_id>)

B_NEC_res_<model_id> – vector field residual (B_NEC - B_NEC_<model_id>)