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Write data to cache

This notebook is meant to be used together with Read data from cache to demonstate the use of the datasets cache.

First we setup a simple experiment. This is copied from another notebook and can be ignored in this context.

%matplotlib notebook
import time

import numpy as np

import qcodes as qc
from qcodes.dataset import Measurement, initialise_database, load_or_create_experiment
from qcodes.instrument_drivers.mock_instruments import (
    DummyInstrument,
    DummyInstrumentWithMeasurement,
)

# preparatory mocking of physical setup

dac = DummyInstrument("dac", gates=["ch1", "ch2"])
dmm = DummyInstrumentWithMeasurement("dmm", setter_instr=dac)

station = qc.Station(dmm, dac)

initialise_database()
exp = load_or_create_experiment(
    experiment_name="dataset_cache_test", sample_name="no sample"
)

Now we are ready to run an experiment. Once this experiment is running, take note of the id of the run (also accessible via dataset.captured_run_id) created and open the Read data from cache notebook and use there this id. After 20 sec this notebook will start writing actual data to the dataset.

# And then run an experiment

meas = Measurement(exp=exp)
meas.register_parameter(dac.ch1)  # register the first independent parameter
meas.register_parameter(dmm.v1, setpoints=(dac.ch1,))  # now register the dependent oone

meas.write_period = 2


with meas.run() as datasaver:
    time.sleep(20)
    # While sleeping here start loader. From load_cached_notebook.ipynb
    # this is done by loading this new run via ``captured_run_id`` printed when the measurement starts
    print("done sleeping")
    for set_v in np.linspace(0, 25, 100):
        dac.ch1.set(set_v)
        get_v = dmm.v1.get()
        datasaver.add_result((dac.ch1, set_v), (dmm.v1, get_v))
        # flush so this always works
        datasaver.flush_data_to_database(block=True)
        time.sleep(0.1)

    dataset = datasaver.dataset  # convenient to have for plotting

Starting experimental run with id: 1.
done sleeping