unitpackage.cv.cv_entry

A Data Package describing a Cyclic Voltammogram found in the field of electrochemistry. It provides additional functionalities compared to the class Entry.

These are the individual elements of a CVCollection.

EXAMPLES:

We can directly access the material of an electrode used in the experiment, such as WE, CE or REF:

>>> from unitpackage.cv.cv_collection import CVCollection
>>> db = CVCollection.create_example()
>>> entry = db['alves_2011_electrochemistry_6010_f1a_solid']
>>> entry.get_electrode('WE').material
'Ru'

The plot() creates a typical representation of a Cyclic Voltammogram, where I or. j is plotted vs. U or. E:

>>> entry.plot()
Figure(...)

class unitpackage.cv.cv_entry.CVEntry(package)

A frictionless data packages describing a Cyclic Voltammogram.

EXAMPLES:

An entry can be created directly from a datapackage that has been created with svgdigitizer’s cv command. However, entries are normally obtained by opening a CVCollection of entries:

>>> from unitpackage.cv.cv_collection import CVCollection
>>> collection = CVCollection.create_example()
>>> entry = next(iter(collection))

get_electrode(name)

Returns an electrode with the specified name.

EXAMPLES:

>>> entry = CVEntry.create_examples()[0]
>>> entry.get_electrode('WE') 
{'name': 'WE', 'function': 'working electrode', 'type': 'single crystal',
'crystallographic orientation': '0001', 'material': 'Ru',
'preparation procedure': 'Sputtering and flash annealing under UHV
conditions with repeated cycles of oxygen adsorption and desorption.',
'shape': {'height': {'unit': 'mm', 'value': 2}, 'type': 'hat shaped'},
'source': {'supplier': 'Mateck'}}

TESTS:

>>> entry.get_electrode('foo') 
Traceback (most recent call last):
...
KeyError: "Electrode with name 'foo' does not exist"

plot(x_label='E', y_label='j', name=None)

Return a plot of this entry. The default plot is a Cyclic Voltammogram (‘j vs E’). When j is not present in the data, I is used instead.

EXAMPLES:

>>> entry = CVEntry.create_examples()[0]
>>> entry.plot()
Figure(...)

The plot can also be returned with custom axis dimensions (field names) available in the resource:

>>> entry.plot(x_label='t', y_label='E')
Figure(...)

A plot resembling the original figure can be obtained by first rescaling:

>>> rescaled_entry = entry.rescale('original')
>>> rescaled_entry.plot()
Figure(...)

rescale(units)

Return a rescaled CVEntry with axes in the specified units.

Usage is essentially the same as for unitpackage.entry.Entry.rescale(), i.e., new units are expected as dict, where the key is the axis name and the value the new unit, such as {'j': 'uA / cm2', 't': 'h'}.

Additionally, the entry can be rescaled to the axes’ units of the original data. These units must be defined in the metadata of the resource, within the key figure_description.fields:

>>> entry = CVEntry.create_examples()[0]
>>> rescaled_entry = entry.rescale(units='original')
>>> rescaled_entry.package.get_resource('echemdb').schema.fields 
[{'name': 't', 'type': 'number', 'unit': 's'},
{'name': 'E', 'type': 'number', 'unit': 'V', 'reference': 'RHE'},
{'name': 'j', 'type': 'number', 'unit': 'mA / cm2'}]

thumbnail(width=96, height=72, dpi=72, **kwds)

Return a thumbnail of the entry’s curve as a PNG byte stream.

EXAMPLES:

>>> entry = CVEntry.create_examples()[0]
>>> entry.thumbnail()
b'\x89PNG...'

The PNG’s width and height can be specified in pixels. Additional keyword arguments are passed to the data frame plotting method:

>>> entry.thumbnail(width=4, height=2, color='red', linewidth=2)
b"\x89PNG..."