Histogram Chart Generator

Inputs

Outputs

Source

python

# Input preparation
inp = __ivy_ctx__["nodes"][__ivy_node_id__]["input"]
title = inp.get("title", "")
data_frame = inp["data_frame"]
x_column = inp["x_column"]
x_axis_title = inp.get("x_axis_title") or inp["x_column"]
y_axis_title = inp.get("y_axis_title", "count")
width = int(inp.get("width", 1200))
height = int(inp.get("height", 600))
format = inp.get("format", "png")

# Compute
import plotly.express as px
import plotly.io as pio
import io

class HistogramChartGenerator:
    """
    A class to generate Plotly charts and export them as image buffers.
    """

    def __init__(self, data_frame):
        """
        Initialize the HistogramChartGenerator with the data frame to use for charts.

        :param data_frame: The data frame containing the data for the charts.
        """
        self.data_frame=data_frame

    def generate(self, x_column: str, title: str, color_sequence=px.colors.sequential.Viridis ):
        """
        Generate a histogram chart.

        :param x_column: The column to use for the x-axis.
        :param title: The title of the chart.
        :param color_sequence: The color sequence for the chart bars.
        :return: A Plotly Figure object.
        """
        self.fig=px.histogram(
            self.data_frame,
            x=x_column,
            title=title,
            color_discrete_sequence=color_sequence
        )

        return self.fig

    def update_layout(self, x_axis_title: str, y_axis_title: str, width: int=1200, height: int=600):
        """
        Update the layout of a Plotly Figure object.

        :param x_axis_title: The title of the x-axis.
        :param y_axis_title: The title of the y-axis.
        :param width: The width of the chart.
        :param height: The height of the chart.
        """
        self.fig.update_layout(
            title_font_size=16,
            xaxis_title=x_axis_title,
            yaxis_title=y_axis_title,
            bargap=0.2,
            width=width,
            height=height
        )

    def export_to_image(self, format: str="png") -> io.BytesIO:
        """
        Export a Plotly Figure object to an image buffer.

        :param format: The format of the image (default: "png").
        :return: A BytesIO buffer containing the image.
        """
        buffer=io.BytesIO()
        pio.write_image(self.fig, buffer, format=format)
        buffer.seek(0)
        return buffer

histogram_chart_generator = HistogramChartGenerator(data_frame=data_frame)

histogram_chart_generator.generate(
    x_column=x_column,
    title=title,
    color_sequence=px.colors.sequential.Viridis
)

histogram_chart_generator.update_layout(
    x_axis_title=x_axis_title,
    y_axis_title=y_axis_title,
    width=width,
    height=height
)

chart_image = histogram_chart_generator.export_to_image(format=format)

# Output collection (runner reads __ivy_ctx__)
out = __ivy_ctx__["nodes"][__ivy_node_id__]["output"]
out["chart_image"] = chart_image
out["size_bytes"] = len(chart_image.getvalue())
out["format"] = format

Tests

Requires: python:3.9, plotly, kaleido

• png-histogram

  A small frame renders to a PNG of a few kilobytes.

• unknown-column

  A column the frame does not have is refused by plotly.