Metys

Metys is scientific report generator and a literate programming tool similar to knitr or Pweave. Like Pweave, Metys uses the Jupyter protocol to run code embedded in the source document. Unlike Pweave, Metys can access multiple Jupyter kernels within the same source document and can also create multiple separate sessions of the same kernel.

Metys is currently alpha level software.

Processing Metys Documents

Metys is currently run from the command line by using the following.

metys foo.tmt

There are many command line options available. A short description will be shown with the following.

metys --help

Input Formats

Metys can parse source documents in noweb, Markdown or Metys format. The format of the source document will be determined by the file extension or by the --parser command line option if specified. Source documents with a file extension ending with nw are assumed to be noweb documents. Those with a file extension ending with md are assumed to be Markdown documents. All other files are assumed to be in Metys format.

Parsing the source document results in a series of logical chunks. These chunks are either text, code or group chunks. Text chunks contain text which is copied verbatim to the output document. Code chunks are evaluated by a Jupyter kernel and the results are formatted in the output document as per the local and global options specified. Group chunks are used to set options for a collection of chunks or to include subfiles which contain more text, code and group chunks.

noweb Format

A document in the noweb format can contain text or code chunks, but not group chunks. Text chunks are preceded by a line containing only an @. Code chunks are preceded by a line containing <<...>>=, where ... represents a list of key/value options. Both text and code chunks are terminated by a marker starting a new chunk. The first chunk in a noweb document is assumed to be a text chunk.

In the sample document below a Maxima kernel is asked to solve a cubic equation, some code is sent to Python and then Maxima is asked to plot a function. Please note that key value options that are missing a value are assumed to a chunk name. In other words <<foo,kernel=python>>= is equivalent to <<name=foo,kernel=python>>=.

Let's ask Maxima to solve a cubic equation.
<<kernel=maxima>>=
solve(x^3+x+1=0,x);
@
Next let Python say hello and have Maxima plot a hyperbolic paraboloid.
<<kernel=python>>=
print('Hello world!')
<<foo, kernel=maxima>>=
plot3d (u^2 - v^2, [u, -2, 2], [v, -3, 3], [grid, 100, 100],
  [mesh_lines_color, false], [svg_plot, "m.svg"]);
@
That's all for now.

Markdown Format

Source documents in the Markdown format can contain text or code chunks, but not group chunks. Code chunks are delimited by a pair of single back-ticks or by a pair of triple back-ticks. This is the same delimiters that plain Markdown uses to indicate code, the difference being that Metys expects a set of key/value options surrounded by curly braces or a set of empty curly braces.

The following sample document accomplishes the same tasks as the previous noweb example. Unlike noweb document key value options without a value are assumed to be a kernel name, not a chunk name.

Let's ask Maxima to solve a cubic equation.

```{maxima}
solve(x^3+x+1=0,x);
```

Next let Python say hello and have Maxima plot a hyperbolic paraboloid.
`{python} print('Hello world!')`

```{maxima, name=foo}
plot3d (u^2 - v^2, [u, -2, 2], [v, -3, 3], [grid, 100, 100],
  [mesh_lines_color, false], [svg_plot, "m.svg"]);
```
That's all for now.

Metys Format

Documents in Metys format can contain text, code or group chunks. Like Markdown the entire document is assumed to be in text mode, so only code and group chunks have delimiters. Both code and group chunks are started by <| and terminated by |>. After the opening delimiter key/value options may be specified until a chunk separator is received. The remainder of the chunk is then either code or group data. The chunk separators are :, | or @. The : separator is used for code blocks, the | separator is used for inline code, and the @ separator is used for group chunks. For example, the following using a group to declare Maxima as the default kernel before making calls to a Maxima kernel and a Python kernel.

<|maxima@
Let's ask Maxima to solve a cubic equation.

<|:solve(x^3+x+1=0,x);|>

Next let Python say hello and have Maxima plot a hyperbolic paraboloid.
<|python|print('Hello world!')|>

<|name=foo:
plot3d (u^2 - v^2, [u, -2, 2], [v, -3, 3], [grid, 100, 100],
  [mesh_lines_color, false], [svg_plot, "m.svg"]);
|>
That's all for now.
|>

Please note that kernels and sessions are local to the innermost enclosing group chunk.

Chunk Options

Chunk options may be specified in all input formats as a list of key/value pairs separated by commas. Each key/value pair consists of a name followed by an equals sign and a value. The absence of an equals sign and a value is treated as a value to be assigned to a default key. The default key for noweb format is name. For all other formats the default key is kernel.

The key name may contain any combination of letters and underscores, along with a single period used to specify sub-options. For example, the following specifies a Maxima kernel, with a LaTeX code environment of Verbatim and frame=single as a verbatim environment option.

<|maxima, code_env=Verbatim, code_env_options.frame=single:
solve(x^3+x+1=0,x);
|>

The table below lists the chunk options available along with a short summary of each option.

Name	Type	Default	Description
code_echo	boolean	true	Enable echo of code input.
code_env	string	verbatim	Code environment for LaTeX.
code_env_options	string/sub-option	None	Code environment options for LaTeX.
evaluate	boolean	true	Enable evaluation of code input.
expand_options	boolean	false	Enable option expansion in code input.
figure_caption	string	None	Figure caption.
figure_env	string	figure	Figure environment for LaTeX.
figure_path	string	figure	Figure directory.
figure_env_options	string/sub-option	None	Figure environment options for LaTeX.
figure_prefix	string	fig:	Figure label prefix for LaTeX.
format	latex, markdown	None	Format of output file.
graphics_options	string/sub-option	None	Graphics options for LaTeX.
inline	boolean	None	Enable inline output format.
input	string	None	Path of input file for chunk.
kernel	string	None	Jupyter kernel.
math_env	string	equation	Display math environment for LaTeX.
math_prefix	string	eq:	Mathematics label prefix for LaTeX.
name	string	None	Chunk name. Used for file names and labels.
output	string	None	Path of output file for chunk.
parser	markdown, metys, noweb	None	Parser to use for input file.
results	boolean	true	Enable output of code results.
session	string	None	Unique identifier for specific kernel session.
stderr_echo	boolean	true	Enable echo of stderr.
stderr_env	string	verbatim	stderr environment for LaTeX.
stderr_env_options	string/sub-option	None	stderr environment options for LaTeX.
stdout_echo	boolean	false	Enable echo of stdout.
stdout_env	string	verbatim	stdout environment for LaTeX.
stdout_env_options	string/sub-option	None	stdout environment options for LaTeX.
wrap_math	boolean	true	Enabling wrapping of math results.

Please not that some options are automatically deduced or may have special behavior. For instance,

• The format option is automatically set if not specified. If parser is set to markdown then the format is also. Otherwise format is set to latex.

• The inline option is automatically set for Markdown and Metys documents, but not for noweb documents.

• The input option has a different behavior for text/code chunks versus group chunks. For group chunks the chunks contents are replaced with the contents of the file specified by input after it has been parsed. For text or code chunks the contents of the file is included without any parsing.

• The kernel option is not set by default but will be set to python for input files with an extension of .Pmd and set to r for input files with an extension of .Rmd.

• The output option will write any chunk output to the file specified by the option versus writing the output to main output document.

• The session option will allow multiple separate sessions of the same kernel to exist. For example, the following document will have two separate Python kernels active. In the default session x has a value of 3, while in the foo session x has a value of 4.

  Wibble <|python|x=3|>, wibble <|python,session=foo|x=4|>, quux <|python|x|>.