pysnirf2

Dynamically generated Python library for reading, writing, and validating Shared Near Infrared Spectroscopy Format (SNIRF) files.

Developed and maintained by the Boston University Neurophotonics Center.

Documentation

Documentation is generated from source using lazydocs

Installation

pip install pysnirf2

pysnirf2 requires Python > 3.6

Features

The library generated via metaprogramming, but the resulting classes explicitly implement each and every specified SNIRF field so as to provide an extensible object-oriented foundation for SNIRF applications.

Open a SNIRF file

Snirf(<path>) opens a SNIRF file at <path> or creates a new one if it doesn't exist.

from pysnirf2 import Snirf
>>> snirf = Snirf(r'some\path\subj1_run01.snirf')

Create a SNIRF file object

Snirf() with no arguments creates a temporary file which can be written later using save().

>>> snirf = Snirf()

Closing a SNIRF file

A Snirf instance wraps a file on disk. It should be closed when you're done reading from it or saving.

>>> snirf.close()

Use a with statement to ensure that the file is closed when you're done with it:

>>> with Snirf(r'some\path\subj1_run01.snirf') as snirf:
>>>      # Read/write
>>>      snirf.save()

View or retrieve a file's contents

>>> snirf
Snirf at /
filename: 
C:\Users\you\some\path\subj1_run01.snirf
formatVersion: v1.0
nirs: <iterable of 2 <class 'pysnirf2.NirsElement'>>

>>> snirf.nirs[0].probe
Probe at /nirs1/probe
correlationTimeDelayWidths: [0.]
correlationTimeDelays: [0.]
detectorLabels: ['D1' 'D2']
detectorPos2D: [[30.  0.]
 [ 0. 30.]]
detectorPos3D: [[30.  0.  0.]
 [ 0. 30.  0.]]
filename: 
C:\Users\you\some\path\subj1_run01.snirf
frequencies: [1.]
landmarkLabels: None
landmarkPos2D: None
landmarkPos3D: None
location: /nirs/probe
momentOrders: None
sourceLabels: ['S1']
sourcePos2D: [[0. 0.]]
sourcePos3D: [[0.]
 [0.]
 [0.]]
timeDelayWidths: [0.]
timeDelays: [0.]
useLocalIndex: None
wavelengths: [690. 830.]
wavelengthsEmission: None

Edit a SNIRF file

Assign a new value to a field

>>> snirf.nirs[0].metaDataTags.SubjectID = 'subj1'
>>> snirf.nirs[0].metaDataTags.SubjectID
'subj1'

>>> snirf.nirs[0].probe.detectorPos3D[0, :] = [90, 90, 90]
>>> snirf.nirs[0].probe.detectorPos3D
array([[90.,  90.,  90.],
      [  0.,  30.,   0.]])

Note: assignment via slicing is not possible in dynamic_loading mode.

Indexed groups

Indexed groups are defined by the SNIRF file format as groups of the same type which are indexed via their name + a 1-based index, i.e. data1, data2, ... or stim1, stim2, stim3, ...

pysnirf2 provides an iterable interface for these groups using Pythonic 0-based indexing, i.e. data[0], data[1], ... or stim[0], stim[1]], stim[2], ...

>>> snirf.nirs[0].stim
<iterable of 0 <class 'pysnirf2.StimElement'>>
>>> len(nirs[0].stim)
0

To add an indexed group, use the appendGroup() method of any IndexedGroup class. Indexed groups are created automatically. nirs is an indexed group.

>>> snirf.nirs[0].stim.appendGroup()
>>> len(nirs[0].stim)
1
>>> snirf.nirs[0].stim[0]
StimElement at /nirs/stim2
data: None
dataLabels: None
filename: 
C:\Users\you\some\path\subj1_run01.snirf
name: None

To remove an indexed group

>>> del snirf.nirs[0].stim[0]

Save a SNIRF file

Overwrite the open file

>>> snirf.save()

Save As in a new location

>>> snirf.save(r'some\new\path\subj1_run01_edited.snirf')

The save() function can be called for any group or indexed group:

>>> snirf.nirs[0].metaDataTags.save('subj1_run01_edited_metadata_only.snirf')

Dynamic loading mode

For larger files, it may be useful to load data dynamically: data will only be loaded on access, and only changed datasets will be written on save(). When creating a new Snirf instance, set dynamic_loading to True (Default False).

>>> snirf = Snirf(r'some\path\subj1_run01.snirf', dynamic_loading=True)

Note: in dynamic loading mode, array data cannot be modified with indices like in the example above:

>>> snirf = Snirf(TESTPATH, dynamic_loading=True)
>>> snirf.nirs[0].probe.detectorPos3D
array([[30.,  0.,  0.],
      [ 0., 30.,  0.]])
>>> snirf.nirs[0].probe.detectorPos3D[0, :] = [90, 90, 90]
>>> snirf.nirs[0].probe.detectorPos3D
array([[30.,  0.,  0.],
       [ 0., 30.,  0.]])

To modify an array in dynamic_loading mode, assign it, modify it, and assign it back to the Snirf object.

>>> detectorPos3D = snirf.nirs[0].probe.detectorPos3D
>>> detectorPos3D[0, :] = [90, 90, 90]
>>> snirf.nirs[0].probe.detectorPos3D = detectorPos3D
array([[90.,  90.,  90.],
       [ 0.,   30.,  0.]])

Validating a SNIRF file

pysnirf2 features functions for validating SNIRF files against the specification and generating detailed error reports.

Validate a Snirf object you have created

>> result = snirf.validate()

Validate a SNIRF file on disk

To validate a SNIRF file on disk

>> from pysnirf2 import validateSnirf
>> result = validateSnirf(r'some\path\subj1_run01.snirf')
>> assert result

Validation results

The validation functions return a ValidationResult instance which contains details about the SNIRF file. To view the validation result:

>> result.display(severity=3)
<pysnirf2.pysnirf2.ValidationResult object at 0x000001C0CCF05A00>
/nirs1/data1/measurementList103/dataType                 FATAL   REQUIRED_DATASET_MISSING
/nirs1/data1/measurementList103/dataTypeIndex            FATAL   REQUIRED_DATASET_MISSING
/nirs1/data1                                             FATAL   INVALID_MEASUREMENTLIST 

Found 668 OK      (hidden)
Found 635 INFO    (hidden)
Found 204 WARNING (hidden)
Found 3 FATAL  

File is INVALID

To look at a particular result:

>> result.errors[2]
<pysnirf2.pysnirf2.ValidationIssue object at 0x000001C0CB502F70>
location: /nirs1/data1
severity: 3   FATAL  
name:     8   INVALID_MEASUREMENTLIST
message:  The number of measurementList elements does not match the second dimension of dataTimeSeries

The full list of validation results result.issues can be explored programatically.

Code generation

The interface and validator are generated via metacode that downloads and parses the latest SNIRF specification.

See \gen for details.