charts.bar-chart

Imports name this capability’s declared dependencies, which fune builds next to it in your project; each one links to its page.

from .charts_axis_band_axis import band_axis
from .charts_axis_grid_lines import grid_lines
from .charts_axis_number_axis import number_axis
from .charts_bar_chart_types import BarChart, BarChartSpec, ChartBar
from .charts_format_format_tick import format_tick
from .charts_layout_legend_rows import legend_rows
from .charts_layout_plot_area import plot_area
from .charts_layout_types import LegendItem, Margins
from .charts_palette import palette  ← from charts.palette ^1.0.0 · built alongside by fune
from .charts_scale_band_scale import band_scale
from .charts_scale_linear_scale import linear_scale
from .charts_scale_nice_domain import nice_domain
from .charts_shape_bar_rects import bar_rects
from .charts_shape_types import BarSpec
from .charts_stack import stack  ← from charts.stack ^1.0.0 · built alongside by fune
from .charts_ticks_nice_ticks import nice_ticks
from .charts_ticks_tick_step import tick_step
from .math_round_float import round_float  ← from math.round-float ^1.0.0 · built alongside by fune

# Fixed layout constants; the README explains each.
CHAR_WIDTH = 7
SWATCH = 10
LEGEND_GAP = 16
LEGEND_ROW = 18
EDGE = 8
TICK_SIZE = 6
LABEL_PADDING = 3
TOP_WITHOUT_LEGEND = 12
RIGHT = 20
BOTTOM = 30
CATEGORY_PADDING_INNER = 0.2
CATEGORY_PADDING_OUTER = 0.1
SERIES_PADDING = 0.05


def bar_chart(spec: BarChartSpec) -> BarChart:
    """A whole bar chart as geometry, by the fixed rules in the README."""
    width, height, categories, series = spec.width, spec.height, spec.categories, spec.series
    if spec.mode not in ("grouped", "stacked"):
        raise ValueError("mode must be grouped or stacked, received %s" % (spec.mode,))
    if len(categories) == 0:
        raise ValueError("a bar chart needs at least one category")
    if len(series) == 0:
        raise ValueError("a bar chart needs at least one series")
    for s in series:
        if len(s.values) != len(categories):
            raise ValueError(
                'series "%s" has %d values but there are %d categories' % (s.name, len(s.values), len(categories))
            )
    names = [s.name for s in series]

    legend = []
    top = TOP_WITHOUT_LEGEND
    if len(series) > 1:
        rows = legend_rows(names, width - 2 * EDGE, CHAR_WIDTH, SWATCH, LEGEND_GAP, LEGEND_ROW)
        legend = [
            LegendItem(
                label=it.label,
                row=it.row,
                x=round_float(it.x + EDGE, 2),
                y=round_float(it.y + EDGE, 2),
                width=it.width,
                text_x=round_float(it.text_x + EDGE, 2),
            )
            for it in rows
        ]
        top = EDGE + (rows[-1].row + 1) * LEGEND_ROW + EDGE

    stacked = stack([list(s.values) for s in series], "diverging") if spec.mode == "stacked" else None
    lo = 0.0
    hi = 0.0
    for i, s in enumerate(series):
        for j, v in enumerate(s.values):
            ends = [v] if stacked is None else [stacked[i][j].y0, stacked[i][j].y1]
            for e in ends:
                if e < lo:
                    lo = e
                if e > hi:
                    hi = e
    if lo == hi:
        hi = 1.0
    y_count = max(2, int((height - top - BOTTOM) // 50))
    y_domain = nice_domain([lo, hi], y_count).domain
    y_step = tick_step(y_domain[0], y_domain[1], y_count)
    widest = 0
    for v in nice_ticks(y_domain[0], y_domain[1], y_count):
        widest = max(widest, len(format_tick(v, y_step)))
    left = TICK_SIZE + LABEL_PADDING + widest * CHAR_WIDTH + EDGE
    plot = plot_area(width, height, Margins(top=top, right=RIGHT, bottom=BOTTOM, left=left))
    bottom_y = plot.y + plot.height
    y_range = [bottom_y, plot.y]

    def y(v: float) -> float:
        return linear_scale(y_domain, y_range, v, False)

    y_axis = number_axis(y_domain, y_range, y_count, "left", plot.x, TICK_SIZE)
    x_range = [plot.x, plot.x + plot.width]
    x_axis = band_axis(
        categories, x_range, CATEGORY_PADDING_INNER, CATEGORY_PADDING_OUTER, "bottom", bottom_y, TICK_SIZE
    )

    colors = palette("okabe-ito", len(series), True)
    specs = []
    meta = []
    for i, s in enumerate(series):
        for j, c in enumerate(categories):
            outer = band_scale(categories, x_range, c, CATEGORY_PADDING_INNER, CATEGORY_PADDING_OUTER, 0.5)
            if stacked is not None:
                specs.append(
                    BarSpec(band=outer.start, thickness=outer.width, base=y(stacked[i][j].y0), value=y(stacked[i][j].y1))
                )
            elif len(series) == 1:
                specs.append(BarSpec(band=outer.start, thickness=outer.width, base=y(0), value=y(s.values[j])))
            else:
                inner = band_scale(names, [outer.start, outer.start + outer.width], s.name, SERIES_PADDING, 0, 0.5)
                specs.append(BarSpec(band=inner.start, thickness=inner.width, base=y(0), value=y(s.values[j])))
            meta.append((s.name, c, s.values[j], colors[i]))
    rects = bar_rects(specs, "vertical")
    bars = [
        ChartBar(series=m[0], category=m[1], value=m[2], color=m[3], rect=rects[k]) for k, m in enumerate(meta)
    ]
    return BarChart(
        width=round_float(width, 2),
        height=round_float(height, 2),
        plot=plot,
        x_axis=x_axis,
        y_axis=y_axis,
        grid_lines=grid_lines(y_axis, plot.width),
        bars=bars,
        colors=list(colors),
        legend=legend,
    )