Source code for node_holdvaluetable

# -*- coding:utf-8 -*-
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import six
import numpy as np
from sympathy.api import node
from sympathy.api import node_helper
from sympathy.api.nodeconfig import Port, Ports, Tag, Tags


def hold_column(array):
    it = iter(np.where(np.isnan(array))[0])
    mask = None

    if isinstance(array, np.ma.core.MaskedArray):
        for i in np.where(array.mask == False)[0]:
            if i > 0:
                mask = np.zeros(len(array), dtype=bool)
                mask[:i] = True
            break

        idx = set()
        maskidx = np.flatnonzero(array.mask)

        idx.update(maskidx)
        idx.update(it)
        it = iter(sorted(idx))

    try:
        i = six.next(it)
    except StopIteration:
        return array

    # Local copy for in-place edit.
    array = np.array(array)

    if i != 0:
        array[i] = array[i - 1]

    for i in it:
        array[i] = array[i - 1]

    if mask is not None:
        return np.ma.MaskedArray(array, mask)

    return array


def hold_table(in_table, out_table):
    for cname in in_table.column_names():
        out_table.set_column_from_array(
            cname, hold_column(in_table.get_column_to_array(cname)))
    out_table.set_attributes(in_table.get_attributes())


class HoldValueTable(node.Node):
    """
    Replace occurences of nan in cells by the last non-nan value from the same
    column.
    """
    author = 'Erik der Hagopian'
    version = '1.0'
    icon = 'drop_nan.svg'
    tags = Tags(Tag.DataProcessing.TransformData)
    description = (
        'Replace occurences of nan in cells by the last non-nan value from '
        'the same column.')

    name = 'Hold value Table'
    nodeid = 'org.sysess.sympathy.data.table.holdvaluetable'

    inputs = Ports([
        Port.Table('Input Table')])
    outputs = Ports([
        Port.Table('Output Table with NaN replaced')])

    def execute(self, node_context):
        hold_table(node_context.input[0], node_context.output[0])


@node_helper.list_node_decorator([0], [0])
class HoldValueTables(HoldValueTable):
    name = 'Hold value Tables'
    nodeid = 'org.sysess.sympathy.data.table.holdvaluetables'