elektro

What is Elektro?

Elektro is the Python client for the Elektro electrophysiology backend — a service for storing, organizing and analysing ephys data (traces, recordings, stimuli, experiments) and the biophysical neuron models behind them.

It splits every object into two halves and keeps them in sync for you: the metadata (a trace's name, its dataset, the experiment it belongs to) lives in a GraphQL API, while the heavy numeric payload (the actual signal, arrays, tables, meshes) is streamed to and from object storage as Zarr and Parquet. You hand Elektro a NumPy array; it uploads the bytes, registers the metadata, and gives you back a typed object whose .data is a lazy xarray.DataArray — so you can ask for trace.data.max() on a multi-gigabyte recording and only the bytes you touch are ever pulled down.

It answers questions like "store this recording and give it back to me as an array I can slice without downloading the whole thing" — and does it as one line of typed, async-first Python.

Note: Elektro is built for the Arkitekt ecosystem. Configuration and authentication come from Fakts, the transport from Rath, and its domain types plug straight into Rekuest workflows.

Installation

pip install elektro

Elektro requires Python ≥ 3.11. Two optional extras pull in heavier, domain-specific dependencies only when you need them:

pip install "elektro[table]"   # pyarrow + pandas + duckdb — query Parquet stores
pip install "elektro[neuron]"  # the NEURON simulator — build & run biophysical models

Scope

Elektro is responsible for the client side of ephys data and nothing else:

1. Modelling — it exposes the Elektro domain (traces, datasets, experiments, simulations, neuron models, …) as typed, validated Python objects generated from the GraphQL schema.
2. Moving data — array-, table- and file-like values you pass into a mutation are transparently uploaded to object storage before the GraphQL call, and read back lazily afterwards. You work with NumPy/xarray; Elektro handles Zarr, Parquet and credentials.
3. Composing — it bundles a GraphQL client (rath) and an object-storage client (datalayer) into one Elektro app, usable sync or async.

It does not run the backend, define the schema, or mint your credentials — those come from the Elektro server and from Fakts / Arkitekt. Elektro is the piece that turns a configured, authenticated connection into typed objects and lazy arrays.

Core concepts

The domain types you work with (all registered as Rekuest structures in elektro/rekuest.py):

Type	Meaning
Trace	A time-series recording — the signal itself, backed by a Zarr store.
Dataset	A named collection that groups traces and other objects.
Experiment	An experimental setup tying together recordings and stimuli.
Recording	A single recording of a trace within an experiment.
Stimulus	A stimulus protocol applied during an experiment.
Block	An organisational unit grouping recordings/stimuli in time.
Simulation	A run of a biophysical neuron model.
NeuronModel	A specific morphology + biophysics model.
ModelCollection	A library of related neuron models.
ROI	A region of interest on a trace.

Heavy payloads enter the API as store-backed scalars (elektro/scalars.py). You pass a plain in-memory value; Elektro uploads it and substitutes a store reference:

Scalar	You pass…	Stored as…
TraceLike	np.ndarray / xr.DataArray	a Zarr store
ArrayLike	an N-dimensional array	a Zarr store
ParquetLike	a pandas / Arrow table	a Parquet store
FileLike	a file path / handle	a big-file store
MeshLike	a 3D mesh	a mesh store

How it fits together

An Elektro app is a small composition of two clients (elektro/elektro.py):

        ┌──────────────────── Elektro ────────────────────┐
        │                                                  │
        │   rath: ElektroRath          datalayer: DataLayer│
        │   (GraphQL metadata)         (object storage)    │
        └───────┬──────────────────────────────┬──────────┘
                │                               │
   write path   │                               │
   from_trace_like(np.ndarray)                  │
                │                               │
        ┌───────▼────────┐   upload bytes   ┌───▼──────────────┐
        │ UploadMiddleware├─────────────────►│  Zarr / Parquet  │
        │ (intercepts the │                  │  object storage  │
        │  array variable)│◄─────────────────┤  (via obstore)   │
        └───────┬────────┘   store id        └───▲──────────────┘
                │                                 │
        ┌───────▼────────┐                        │  lazy reads
        │ GraphQL mutation│  carries store id      │
        │ via ElektroRath │                        │
        └───────┬────────┘                        │
                │                                  │
   read path    │  Trace                           │
        trace.data  ──── HasZarrStoreTrait ───────►│  xr.DataArray
                       (only the bytes you touch are pulled)

The write path: you call from_trace_like(array, …); UploadMiddleware (elektro/middleware/upload.py) pulls the array out of the variables, uploads it to a Zarr store through the datalayer, and the GraphQL mutation only ever carries the resulting store id. The read path: the returned Trace mixes in HasZarrStoreTrait, whose .data property opens that Zarr store as a lazy xarray.DataArray — nothing is downloaded until you compute.

Quickstart

In the Arkitekt ecosystem the app is built and entered for you, and the top-level schema functions in elektro.api.schema operate against the current connection:

import numpy as np
from elektro.api.schema import create_dataset, from_trace_like, get_random_trace
from arkitekt import easy

# Create a dataset (metadata only)
with easy():
        dataset = create_dataset(name="my_experiment")

        # Upload a 1-D signal — the array is stored in Zarr, the metadata in GraphQL
        trace = from_trace_like(
        np.random.random((1000,)),
        name="signal_1",
        dataset=dataset.id,
        )

        trace.id           # the new trace's id
        trace.data.shape   # (1000,) — a lazy xarray.DataArray, materialized on access

        # Fetch one back
        again = get_random_trace()

Every function has an a-prefixed async twin (acreate_dataset, afrom_trace_like, aget_random_trace, …) for use inside an async context:

dataset = await acreate_dataset(name="my_experiment")
trace = await afrom_trace_like(np.random.random((1000,)), name="signal_1", dataset=dataset.id)

Outside Arkitekt you can construct the app yourself — Elektro(rath=ElektroRath(...), datalayer=DataLayer(...)) — and use it as a context manager (with elektro: ...). See tests/conftest.py for a full manual wiring against a local deployment.

Working with data

Lazy arrays. A Trace (and anything mixing in HasZarrStoreTrait) exposes its payload as an xarray.DataArray that is only fetched on demand:

data = trace.data                 # xr.DataArray (lazy, dask-backed)
peak = data.max().compute()       # pulls only what it needs
trace.multi_scale_data            # list[xr.DataArray] — the multiscale pyramid
trace.export_csv("signal.csv")    # dump the trace to CSV

Tables. Parquet-backed stores expose a queryable relation (requires elektro[table]):

relation = store.duckdb_relation  # a duckdb.DuckDBPyRelation you can SQL against
df = store.parquet_dataset        # the underlying Parquet dataset

Files & meshes. Big-file and media stores download to disk on request:

path = bigfile_store.download()              # → local file path
path = media_store.download("frame.png")     # presigned download

Units. Physical quantities are real pint quantities via kanne (Milliseconds, Micrometers, Microliters, …), coerced on the wire by CoercePintLink so the server always receives canonical units.

Neuron modelling

Elektro models biophysical neurons as a typed hierarchy — ModelConfig → Cell → Topology (sections & connections) → Biophysics (mechanisms & conductances) → Compartment. The input traits (elektro/traits.py) make these easy to build and inspect:

config.as_input()            # ModelConfig → its GraphQL input form
biophysics.as_dataframe()    # inspect compartments/mechanisms as a pandas DataFrame

With the elektro[neuron] extra installed, elektro/neuron/ parses NEURON .mod mechanism files and runs simulations directly from a ModelConfig, recording the result as a Simulation.

In the Arkitekt ecosystem

• ElektroService (elektro/arkitekt.py) — registers Elektro as an Arkitekt service. It builds a fully wired Elektro app from a Fakts config (FaktsAuthLink for auth, FaktsAIOHttpLink/FaktsGraphQLWSLink for transport, a FaktsDataLayer for storage) so an Arkitekt app gets a ready-to-use client with no manual setup.
• structure_reg (elektro/rekuest.py) — registers the domain types (Trace, Dataset, Experiment, Simulation, …) as Rekuest structures, each under an identifier like @elektro/trace, so they can be passed in and out of Rekuest workflow nodes (expand/shrink/search handled for you).

Under the hood the transport is Rath (ElektroRath, a link chain of file extraction, dicting, pint coercion, auth and an HTTP/WebSocket split), the composition is koil, and object storage goes through obstore + Zarr/Parquet.

Public API

from elektro import Elektro, ElektroService, structure_reg

# the building blocks of the app
from elektro.rath import ElektroRath
from elektro.datalayer import DataLayer

# the domain operations (turms-generated; sync + async `a*` twins)
from elektro.api.schema import (
    create_dataset,
    from_trace_like,
    get_random_trace,
    create_experiment,
    create_simulation,
    Trace,
    Dataset,
)

elektro.api.schema is generated from the GraphQL schema by turms and regenerated whenever the schema changes — it is the source of truth for the full set of available operations and types.

Development

uv sync
uv run pytest

Integration tests spin up a real Elektro + MinIO deployment with testcontainers and are marked @pytest.mark.integration; tests needing the NEURON simulator are marked @pytest.mark.neuron. Run just the fast suite with uv run pytest -m "not integration and not neuron".

See RELEASING.md for the semantic-release flow (main → stable, next → rc prereleases, N.x → maintenance).