Rectangle selection

In this example, we will use a custom drawing tool to draw rectangles on a 2D figure. The data inside the rectangles will be summed along the vertical dimension, and displayed on a one-dimensional plot below the image.

%matplotlib widget
import plopp as pp
import scipp as sc
import numpy as np

We first generate some data that contains three bands of peaks that all have different spreads.

from plopp.data.examples import three_bands

da = three_bands()

We then construct our custom tool, using Mpltoolbox’s Rectangles tool, and inheriting from Plopp’s DrawingTool.

from plopp.widgets.drawing import DrawingTool
from functools import partial
from mpltoolbox import Rectangles


def vertical_sum(da, rect_info):
    """
    Function that slices the data according to the
    rectangle size/position, and sums along the
    vertical dimension.
    """
    x = rect_info['x']
    y = rect_info['y']
    b = min(y['bottom'], y['top'])
    t = max(y['bottom'], y['top'])
    l = min(x['left'], x['right'])
    r = max(x['left'], x['right'])
    return da[y['dim'], b:t][x['dim'], l:r].sum(y['dim'])


def _get_rect_info(artist, figure):
    """
    Convert the raw rectangle info to a dict containing the dimensions of
    each axis, and values with units.
    """
    return lambda: {
        'x': {
            'dim': figure.canvas.dims['x'],
            'left': sc.scalar(artist.xy[0], unit=figure.canvas.units['x']),
            'right': sc.scalar(
                artist.xy[0] + artist.width, unit=figure.canvas.units['x']
            ),
        },
        'y': {
            'dim': figure.canvas.dims['y'],
            'bottom': sc.scalar(artist.xy[1], unit=figure.canvas.units['y']),
            'top': sc.scalar(
                artist.xy[1] + artist.height, unit=figure.canvas.units['y']
            ),
        },
    }


RectangleTool = partial(
    DrawingTool, tool=Rectangles, get_artist_info=_get_rect_info, icon='vector-square'
)

Finally, we create our visualization interface with two figures, adding our new tool to the toolbar.

from plopp.widgets import Box

data_node = pp.Node(da)

f2d = pp.imagefigure(data_node, norm='log')
f1d = pp.linefigure()

r = RectangleTool(figure=f2d, input_node=data_node, func=vertical_sum, destination=f1d)
f2d.toolbar['roi'] = r

box = Box([f2d, f1d])

box

pp.show_graph(data_node)