File Format

Files in the database can be in two different formats. Either as a text file (.txt, .csv or .nk) or as a YAML file (.yml). An example of each format is generated in the UserData module when installing the package.

Text File

This is an example of the text file format,

# This is a multiline meta-comment
# which provides information not
# in metadata
# REFERENCES: Literature reference to the data
# AUTHOR: The author of this data file
# FULLNAME: Full name of the material
# NAME: Short name of the material
# COMMENTS: Any additional information goes here
# SPECTRUMTYPE: wavelength
# UNIT: nanometer
# DATATYPE: tabulated nk
#
400.00000000  1.70000000      0.10000000
500.00000000  1.60000000      0.05000000
600.00000000  1.50000000      0.00000000
700.00000000  1.40000000      0.00000000

• The optional metacomment comes at the beginning and can span multiple lines, each line must begin with # for .txt and .csv or ; for .nk files.
• The optional metadata is written in key:value pairs, one per line, beginning with a # (.txt, .csv) or ; (.nk). For a list of valid metadata categories, see MetaData.
• Text files are restricted to datasets of tabulated data. For data defined via model parameters, use the YAML format.
• .txt and .nk files expect tab separated columns, .csv files should use comma separated columns.

YAML File

This is an example of the yaml file format,

# This is a multiline meta-comment
# which provides information not
# in metadata

REFERENCES: Literature reference to the data
COMMENTS: Any additional information goes here
NAME: Short name of the material
FULLNAME: Full name of the material
AUTHOR: The author of this data file
DATA:
  - DataType: model Sellmeier
    ValidRange: 0.35 2.
    SpectrumType: wavelength
    Unit: micrometer
    Yields: n
    Parameters: 0.    1.    0.05  2.    0.1  10.   25.
  - DataType: tabulated k
    ValidRange: 400. 600.
    SpectrumType: wavelength
    Unit: nm
    Data: |-
        4.e+02 1.e-01
        5.e+02 5.e-02
        6.e+02 0.e+00

• The optional metacomment comes at the beginning and can span multiple lines, each line must begin with #.
• The optional metadata is written in key:value pairs, one per line. For a list of valid metadata categories, see MetaData.
• The DATA section can contain one or more data sets. Each data set after DATA: begins with a “-“.
• Each type of data set can contain different types of metadata.

MetaData

Metadata is divided into two kinds, metadata for the file, and metadata for each dataset.

File Metadata

REFERENCES

Literature reference to the data

COMMENTS

Any additional information

NAME

Short name of the material

FULLNAME

Full name of the material

AUTHOR

The author of the data file

Dataset Metadata

DataType

{tabulated_n, tabulated_k, tabulated_nk, tabulated_eps, model} For valid model names see The SpectralData Class

SpectrumType

The type of spectrum. For more information see The Spectrum Class

Unit

The physical unit of the spectrum. For more information see The Spectrum Class

ValidRange

The spectral range that this data set covers

Data

For tabulated data sets, the table of data.

Yields

For model datasets, what values the model returns

Parameters

For model datasets, the parameters or coefficients for the model