Mark cells as active only in ipynb with cell tags

Fixes #226

HISTORY.rst

@@ -9,6 +9,7 @@ Release History
 **Improvements**
 
 - Jupytext's content manager has a new option `notebook_extensions` (#224, #183)
+- Cells can be made inactive in scripts with the `active-ipynb` cell tag (#226)
 
 **BugFixes*
 

README.md

@@ -77,7 +77,7 @@ In the animation below we propose a quick demo of Jupytext. While the example re
 Jupytext allows to import code from other Jupyter notebooks in a very simple manner. Indeed, all you need to do is to pair the notebook that you wish to import with a script, and import the resulting script.
 
 If the notebook contains demos and plots that you don't want to import, mark those cells as either
-- _active_ only in the `ipynb` format, with the `{"active": "ipynb"}` cell metadata
+- _active_ only in the `ipynb` format, with the `{"active": "ipynb"}` cell metadata, or with an `active-ipynb` tag (you may use the [jupyterlab-celltags](https://github.com/jupyterlab/jupyterlab-celltags) extension for this).
 - _frozen_, using the [freeze extension](https://jupyter-contrib-nbextensions.readthedocs.io/en/latest/nbextensions/freeze/readme.html) for Jupyter notebook.
 
 Inactive cells will be commented in the paired script, and consequently will not be executed when the script is imported.

jupytext/cell_metadata.py

@@ -245,7 +245,7 @@ def rmd_options_to_metadata(options):
     for name in metadata:
         try_eval_metadata(metadata, name)
 
-    if ('active' in metadata or metadata.get('run_control', {}).get('frozen') is True) and 'eval' in metadata:
+    if 'eval' in metadata and not is_active('.Rmd', metadata):
         del metadata['eval']
 
     return metadata.get('language') or language, metadata
@@ -351,6 +351,9 @@ def is_active(ext, metadata):
     """Is the cell active for the given file extension?"""
     if metadata.get('run_control', {}).get('frozen') is True:
         return False
+    for tag in metadata.get('tags', []):
+        if tag.startswith('active-'):
+            return ext.replace('.', '') in tag.split('-')
     if 'active' not in metadata:
         return True
     return ext.replace('.', '') in re.split('\\.|,', metadata['active'])

tests/test_active_cells.py

@@ -84,6 +84,37 @@ def test_active_ipynb(ext):
         compare(nb.cells[0], ACTIVE_IPYNB['.ipynb'])
 
 
+ACTIVE_IPYNB_RMD_USING_TAG = {'.py': """# + {"tags": ["active-ipynb-Rmd"]}
+# # This cell is active only in ipynb and Rmd
+# %matplotlib inline
+""",
+                              '.Rmd': """```{python tags=c("active-ipynb-Rmd")}
+# This cell is active only in ipynb and Rmd
+# %matplotlib inline
+```
+""",
+                              '.R': """# + {"tags": ["active-ipynb-Rmd"]}
+# # This cell is active only in ipynb and Rmd
+# %matplotlib inline
+""",
+                              '.ipynb': {'cell_type': 'code',
+                                         'source': '# This cell is active only in ipynb and Rmd\n'
+                                                   '%matplotlib inline',
+                                         'metadata': {'tags': ['active-ipynb-Rmd']},
+                                         'execution_count': None,
+                                         'outputs': []}}
+
+
+@skip_if_dict_is_not_ordered
+@pytest.mark.parametrize('ext', ['.Rmd', '.py', '.R'])
+def test_active_ipynb_rmd_using_tags(ext):
+    with mock.patch('jupytext.header.INSERT_AND_CHECK_VERSION_NUMBER', False):
+        nb = jupytext.reads(HEADER[ext] + ACTIVE_IPYNB_RMD_USING_TAG[ext], ext)
+        assert len(nb.cells) == 1
+        compare(ACTIVE_IPYNB_RMD_USING_TAG[ext], jupytext.writes(nb, ext))
+        compare(nb.cells[0], ACTIVE_IPYNB_RMD_USING_TAG['.ipynb'])
+
+
 ACTIVE_IPYNB_RSPIN = {'.R': """#+ active="ipynb", eval=FALSE
 # # This cell is active only in ipynb
 # 1 + 1