Input and output (IO) of information from and to the persistence layer.

Supported file formats

Currently, a number of more or less well-known and widely used EPR file formats are supported:




Bruker ESP and EMX

par, spc

Bruker BES3T


Magnettech (now Bruker) XML



lmb, exp, dat

Generic text file


For further details, you may have a look at the module documentation of the individual importer.

General usage

A normal user of the cwepr package will not need to interact explicitly and directly with the importers, as they are using recipe-driven data analysis. See the use cases section for an introduction. Here, importing data is a matter of specifying a list of datasets:

  - /path/to/my/first/dataset
  - /path/to/my/second/dataset

The cwepr package will take care of finding the correct importer for you, thanks to using the` class.

Nevertheless, sometimes you would like to have a bit more control over the imported datasets, directly setting IDs for referring to the individual datasets from within the recipe and a label that would show up, i.a., in the legend of plots:

  - source: /path/to/my/first/dataset
    label: cool dataset
    id: data
  - source: /path/to/my/second/dataset
    label: resonator background
    id: background

It should be quite obvious what happens here. Nevertheless, a bit of an explanation:

  • The list of paths got transformed into a list of dictionaries, if you like, i.e., key–value pairs, for each dataset.

  • The path to the file needs to be given as source attribute.

  • The label attribute allows to set a label used, i.a., in figure legends.

  • The id allows to set a short, memorable name for the dataset you can use to refer to it from within the recipe. This is quite useful particularly with longer and more complicated paths.

In rare cases, you may have the need of explicitly controlling the importer used to import your data, and perhaps provide some additional parameters to the importer as well. Typical use cases would be importing text files:

  - source: eprdata.txt
        delimiter: '        '
        separator: ','
        skiprows: 3
        comments: '%'

Here, the delimiter between columns is the tabulator, the decimal separator the comma, the first three lines are skipped by default as well as every line starting with a percent character, as this is interpreted as comment.

A frequent use case is importing simulations that were carried out with EasySpin. A MATLAB excerpt for saving the simulated spectrum might look as follows:

[B_sim_iso, Spc_sim_iso] = garlic(Sys, Exp);

data = [B_sim_iso', Spc_sim_iso'];
writematrix(data, 'Simulated-spectrum')

Read in the simulated spectrum with:

  - source: Simulated-spectrum.txt
    id: simulation
    importer: TxtImporter
        delimiter: ','

Have a look at the documentation of the individual importer modules, as well as the documentation of the ASpecD module:


Data without context, read: metadata, are usually useless. Hence, it is strongly recommended to provide appropriate metadata for your EPR data. Have a look at the section on metadata in the general user documentation of the cwepr package.


All importers implemented in the cwepr package should automatically read Infofiles if they are present. Hence, this is a comparably easy and straight-forward way to collect metadata during data acquisition in a machine-readable way and to have those metadata accessible from within the cwepr package.


Generally, for each file format (or class of formats), the importer resides in a separate module. This is due to the rather complicated nature of some importers (or, more exactly, the underlying file format). For details of the available importers, have a look at the supported file formats section above.

In addition to modules for the individual data file formats, there are a series of more general modules: