create_image_block

I wrote a Block extension (code is below) that converts pyplot instructions to plots inserted into the document. Problems:

1. create_image_block throws error "`image': undefined method `include?' for nil:NilClass". What is the correct calling syntax? I have the file name and caption.
2. Once the entire document is parsed, python needs to be called (at_end method in code below). How can I get the asciidoctor processor to call at_end after parsing?
3. Is there a way to get the path of the document being processed? Would be useful to put the generated figures in the right place.

Many thanks!
Bernhard

Code:

require 'asciidoctor/extensions' unless RUBY_ENGINE == 'opal'

include Asciidoctor

# Inserts pyplot image.
#
# Usage
#
#   [pyplot]
#   ----
#   plot([1,2,3,4])
#   title('pyplot test')
#   ----
#
require 'asciidoctor/extensions' unless RUBY_ENGINE == 'opal'
require 'date'

include Asciidoctor

# Create pyplot
#
# Usage
#
#   plot([1,2,3])
#
class PyplotBlock < Extensions::BlockProcessor

  use_dsl

  named :pyplot
  on_context :listing
  parse_content_as :simple
  name_attributes 'caption'

  PY_FILE = "pyplot.py"
  PL_FILE = "py_fig_%d.svg"
  @@counter = 0   # number of plot

  def process parent, reader, attrs

    if @@counter < 1
      # create PY_FILE with header
      File.open(PY_FILE, 'w') do |fo|
        fo.puts "\# machine generated by PyplotBlock on #{DateTime.now}"
        fo.puts "from pylab import *"
      end
    end

    @@counter += 1
    fig_file = PL_FILE % @@counter
    caption = (attrs.delete 'caption') || ''

    File.open(PY_FILE, 'a') do |fo|
      fo.puts
      fo.puts "%s #{fig_file}: #{caption}" % ('#'*5)
      fo.puts "clf()"
      fo.puts reader.source_lines
      fo.puts "tight_layout()"
      fo.puts "savefig('#{fig_file}')"
    end

    # create_image_block raises following error:
    # asciidoctor/converter/html5.rb:552:in `image': undefined method `include?' for nil:NilClass (NoMethodError)
    create_image_block parent, file_name:fig_file, title:caption
  end

  # call this after parsing entire document
  # (renders plots)
  def at_end
    system("python #{PY_FILE}")
  end
end

Asciidoctor::Extensions.register do
  block PyplotBlock
end

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NAML

@mojavelinux,

Thank you very much for the response. My code (below) works now.

The only part that does not is I don't get a Figure caption and number with the image. But I can live with that.

Bernhard


```
require 'asciidoctor/extensions' unless RUBY_ENGINE == 'opal'

include Asciidoctor

# Inserts pyplot image.
#
# Usage
#
#   [pyplot]
#   ----
#   plot([1,2,3,4])
#   title('pyplot test')
#   ----
#
require 'asciidoctor/extensions' unless RUBY_ENGINE == 'opal'
require 'date'

include Asciidoctor

# Create pyplot
#
# Usage (see pyplot.adoc)
#
#    .Title of this pyplot
#    [pyplot]
#    ----
#    def f(t):
#      return cos(2 * pi * t) * exp(-t)
#    t = linspace(0, 5, 500)
#
#    plot(t, f(t))
#    title("Damped exponential decay")
#    text(3, 0.15, r"$y = \cos(2 \pi t) e^{-t}$")
#    xlabel("Time [s]")
#    ylabel("Voltage [mV]")
#    ----
#
# then run
#    python3 pyplot.py
#
class PyplotBlock < Extensions::BlockProcessor

  use_dsl
  named :pyplot
  on_context :listing
  parse_content_as :simple

  PY_FILE = "%s/pyplot.py"
  PL_FILE = "%s/figures/py_fig_%d.svg"
  @@counter = 0   # number of plot

  def process parent, reader, attrs

    base_dir = parent.document.base_dir
    attributes = parent.document.attributes
    prefix     = attributes['pyplot_prefix']  || "clf();  figure(figsize=(5,4))"
    postfix    = attributes['pyplot_postfix'] || "tight_layout()"
    pyfile     = PY_FILE % base_dir

    if @@counter < 1
      # create PY_FILE with header
      File.open(pyfile, 'w') do |fo|
        fo.puts "\# machine generated by PyplotBlock on #{DateTime.now}"
        fo.puts "from pylab import *"
        fo.puts "import os"
        fo.puts "rc('text', usetex=True)"
        fo.puts "os.makedirs(os.path.dirname('#{PL_FILE}'), exist_ok=True)" % [ base_dir, 0 ]
      end
    end

    @@counter += 1
    attrs['target'] = PL_FILE % [ base_dir, @@counter ]
    attrs['numbered'] = true   # wish this would label and number captions but doesn't ...
    File.open(pyfile, 'a') do |fo|
      fo.puts
      fo.puts "%s #{attrs['target']}: #{attrs['title']}" % ('#'*5)
      fo.puts prefix
      fo.puts reader.source_lines
      fo.puts postfix
      fo.puts "savefig('#{attrs['target']}')"
    end
    # puts "attrs  = #{attrs}"
    create_image_block parent, attrs
  end

  # call this after parsing entire document
  # (renders plots)
  def at_end
    system("python3 #{PY_FILE}")
  end
end

Asciidoctor::Extensions.register do
  block PyplotBlock
end
```

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NAML

All works perfect now, thanks!
In the end, I prefer to run python manually when needed as it is much slower than document rendering. Below are the code and an example, in case someone else has a need.
Extension to convert inline python code to plots:

require 'asciidoctor/extensions' unless RUBY_ENGINE == 'opal'

include Asciidoctor

# Inserts pyplot image.
#
# Usage
#
#   [pyplot]
#   ----
#   plot([1,2,3,4])
#   title('pyplot test')
#   ----
#
require 'asciidoctor/extensions' unless RUBY_ENGINE == 'opal'
require 'date'

include Asciidoctor

# Create pyplot
#
# Usage (see pyplot.adoc)
#
#    .Title of this pyplot
#    [pyplot]
#    ----
#    def f(t):
#      return cos(2 * pi * t) * exp(-t)
#    t = linspace(0, 5, 500)
#
#    plot(t, f(t))
#    title("Damped exponential decay")
#    text(3, 0.15, r"$y = \cos(2 \pi t) e^{-t}$")
#    xlabel("Time [s]")
#    ylabel("Voltage [mV]")
#    ----
#
# then run
#    python3 pyplot.py
#
class PyplotBlock < Extensions::BlockProcessor

  use_dsl
  named :pyplot
  on_context :listing
  parse_content_as :simple

  PY_FILE = "pyplot.py"
  PL_FILE = "figures/pyplot/py_fig_%d.svg"
  @@counter = 0   # number of plot

  def process parent, reader, attrs

    base_dir = parent.document.base_dir
    attributes = parent.document.attributes
    prefix     = attributes['pyplot_prefix']  || "clf();  figure(figsize=(5,4))"
    postfix    = attributes['pyplot_postfix'] || "tight_layout()"
    pyfile     = PY_FILE

    if @@counter < 1
      # create PY_FILE with header
      File.open(pyfile, 'w') do |fo|
        fo.puts "\# machine generated by PyplotBlock on #{DateTime.now}"
        fo.puts "from pylab import *"
        fo.puts "import os"
        fo.puts "rc('text', usetex=True)"
        fo.puts "os.makedirs(os.path.dirname('#{PL_FILE}'), exist_ok=True)" % 0
      end
    end

    @@counter += 1
    attrs['target'] = PL_FILE % @@counter
    attrs['numbered'] = true   # wish this would label and number captions but doesn't ...
    File.open(pyfile, 'a') do |fo|
      fo.puts
      fo.puts "%s #{attrs['target']}: #{attrs['title']}" % ('#'*5)
      fo.puts prefix
      fo.puts reader.source_lines
      fo.puts postfix
      fo.puts "savefig('#{attrs['target']}')"
    end
    # puts "attrs  = #{attrs}"
    img = create_image_block parent, attrs
    img.title = attrs['title']
    img.assign_caption nil, 'figure'
    img
  end

  # call this after parsing entire document
  # (renders plots)
  # Note: slow. Do this only when needed (from the command line).
  def at_end
    system("python3 #{PY_FILE}")
  end
end

Asciidoctor::Extensions.register do
  block PyplotBlock
end

Sample document:

= PyPlot test
:xrefstyle: short
:pyplot_prefix: clf();  figure(figsize=(5,4))
:pyplot_postfix: tight_layout()

Create plots from in-line python code.
Run this through asciidoctor

```
asciidoctor -r ~/Dropbox/Files/Lib/Adoc/ext/pyplot.rb
```

then create the figures with

```
python3 pyplot.py
```

<> is a python plot. <> is another.

[[exp_plot]]
.Plot of exponential decay showing off asciidoctor pyplot extension
[pyplot]
----
def f(t):
  return cos(2 * pi * t) * exp(-t)
t = linspace(0, 5, 500)

# Generate the plot with annotations
plot(t, f(t))
title("Damped exponential decay")
text(3, 0.15, r"$y = \cos(2 \pi t) e^{-t}$")
xlabel("Time [s]")
ylabel("Voltage [mV]")
grid(True)
----

[[lin_plot]]
.Piecewise linear
[pyplot]
----
plot([3, 9, -2])
----

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NAML

That's what I wanted until I realized that the python step is much slower than formatting the adoc.

So I run python only occasionally when I've added a new plot, not to slow down the live view.

Thanks,
Bernhard

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NAML