PyDapsys - Read DAPSYS recordings with Python

PyDapsys is a package to read neurography recordings made with DAPSYS (Data Acquisition Processor System). It is based on a reverse-engineered specification of the binary data format used by the latest DAPSYS version.

Optionally, the library provides functionality to store loaded data into Neo datastructures, from where they can be exported into various other formats.

Installation

Either download the wheel file for offline installation or use pypi.

Basic functionalities

Will only offer the data representation of PyDapsys, without ability to convert to Neo. Has only numpy as sole dependency.

pip install pydapsys

pip install {name_of_downloaded_wheel}.whl

With Neo converters

Install base library with additional dependencies required to load data into Neo datastructures. Writing Neo datastructures to some formats may require additional dependencies. Please see the Neo documentation for further information.

pip install pydapsys[neo]

pip install {name_of_downloaded_wheel}.whl[neo]

Usage

Quickstart

A DAPSYS file is made up of two parts: A sequential list of blocks or pages, which store either a text with a timestamp or a waveform with associated timestamps, and a table of contents (toc). The toc consists of folders and streams. Each page has an id unique in the context of the file. Streams in the toc have an array of ids of the pages belonging to the stream. A stream is either a text stream (referring only to text pages) or a data stream (referring only to recording pages).

Load a file

Use File.from_binary to read from a BinaryIO object.

from pydapsys import read_file
from pathlib import Path
MY_DAPSYS_FILE = Path(".")/"to"/"my"/"dapsys_file.dps"
with open(MY_DAPSYS_FILE, 'rb') as file:
    file = read_file(file)

The File object has two fields, the root of the table of contents and a dictionary mapping the page ids to their respective pages.

Inspect file structure

To inspect the ToC structure of a loaded file, use the structure property of the toc Root, preferable together with pprint:

import pprint
pprint.PrettyPrinter(indent=4).pprint(file.toc.structure)

This will print the structure, names and types of all elements in the table of contents. For Streams, the number of associated pages it also printed after their type.

Access data from a file

To access data, use the File.get_data method. The method takes a path from the toc structure (WITHOUT THE NAME OF THE ROOT!) and will return all associated pages. Please note, that the path is case insensitive

from pydapsys.toc import StreamType
my_texts = list(file.get_data("myrecording/my text stream", stype=StreamType.Text))
my_waveforms = list(file.get_data("myrecording/somewhere else/ my waveform stream", stype=StreamType.Waveform))

Text pages

A text page consists of three fields:

• text: The text stored in the page, string

• timestamp_a: The first timestamp of the page, float64 (seconds)

• timestamp_b: The second timestamp of the page (float64, seconds), which sometimes is not presented and is thus set to None

Waveform pages

Waveform pages consist of three fields:

• values: Values of the waveform, float32 (volt)

• timestamps: Timestamps corresponding to values, float64 (seconds)

• interval: Interval between values, float64 (seconds)

In continuously sampled waveforms, only the timestamp of the first value will be present, in addition to the sampling interval. The timestamps of the other values can be calculated by this two values.

Irregularly sampled waveforms will have one timestamp for each value, but no interval.

Neo converters

The module pydapsys.neo_convert contains classes to convert a Dapsys recording to the Neo format. IMPORTANT: importing the module without installing neo first will raise an exception

As Dapsys files may have different structures, depending on how it was configured and what hardware is used, different converters are required for each file structure.

Currently there is only one converter available, for recordings made using a NI Pulse stimulator.

NI Pulse stimulator

Converter class for Dapsys recording created using an NI Pulse stimulator. Puts everything into one neo sequence. Waveform pages of the continuous recording are merged if the difference between a pair of consecutive pages is less than a specified threshold (grouping_tolerance).

from pydapsys.neo_converters import NIPulseStimRecordingConverter

# convert a recording to a neo block
neo_block = NIPulseStimRecordingConverter(file, grouping_tolerance=1e-9).to_neo()

Expected file structure

{stim_folder} must be one of "NI Puls Stimulator", "pulse stimulator", "NI Pulse stimulator", but can be changed by adding entries to NIPulseStimulatorToNeo.stim_foler_names

• Root

  • [Text] Comments -> Converted into a single event called "comments"

  • {stim_folder}

    • [Text] Pulses -> Converted into one neo event streams, one per unique text

    • [Waveform] Continuous recording -> Converted into multiple AnalogSignals

    • Responses

      • Tracks for All Responses -> Optional. Will silently ignore spike trains if this folder does not exist

        • ... [Text] tracks... -> Converted into spike trains