Predefined nodes

Preparing data for plotting

Data Selection

To be written. Describe data selector, idea of compatible data.

Data Gridding

Converting data from a tabular format to a grid is done by the by the node class DataGridder:

class plottr.node.grid.DataGridder(name)

A node that can put data onto or off a grid. Has one property: grid. Its possible values are governed by a main option, plus (optional) additional options.

property grid

Specification for how to grid the data. Consists of a main option and (optional) additional options.

The main option is of type GridOption, and the additional options are given as a dictionary. Assign as tuple, like:

>>> dataGridder.grid = GridOption.<option>, dict((**options)

All types of GridOption are valid main options:

• GridOption.noGrid –

  will leave tabular data as is, and flatten gridded data to result in tabular data

• GridOption.guessShape –

  use guess_shape_from_datadict() and datadict_to_meshgrid() to infer the grid, if the input data is tabular.

• GridOption.specifyShape –

  reshape the data using a specified shape.

• GridOption.metadataShape –

  use the shape specified in the dataset metadata

Some types may required additional options. At the moment, this is only the case for GridOption.specifyShape. Manual specification of the shape requires two additional options, order and shape:

• order –

  a list of the input data axis dimension names, in the internal order of the input data array. This order is used to transpose the data before re-shaping with the shape information. Often this is simply the axes list; then the transpose has no effect. A different order needed when the the data to be gridded is not in C order, i.e., when the axes order given in the DataDict is not from slowest changing to fastest changing.

• shape –

  a tuple of integers that can be used to reshape the input data to obtain a grid. Must be in the same order as order to work correctly.

See data.datadict.datadict_to_meshgrid() for additional notes; order will be passed to inner_axis_order in that function, and shape to target_shape.

Return type

Tuple[GridOption, Dict[str, Any]]

class plottr.node.grid.GridOption

Options for how to grid data.

guessShape = 1

guess the shape of the grid

metadataShape = 3

read the shape from DataSet Metadata (if available)

noGrid = 0

don’t put on a grid

specifyShape = 2

manually specify the shape of the grid

Data slicing and reduction to 1D or 2D

To be written.