app.py

import math

import numpy as np
import pandas as pd
import requests
import seaborn as sns
import streamlit as st
from matplotlib import pyplot as plt

COLUMN_DISPLAY = [
    "code",
    "shape",
    "number_of_units",
    "material",
    "weight",
    "is_main_component",
    "weight_all_units",
    "quantity_per_unit",
    "product_quantity",
]


@st.cache_data
def get_category_names():
    category_names = {}
    items = requests.get(
        "https://static.openfoodfacts.org/data/taxonomies/categories.json"
    ).json()
    for id_, item in items.items():
        category_names[id_] = item["name"].get("en", id_)
    return category_names


@st.cache_data
def get_base_df(drop_uncomplete: bool = True):
    df = pd.read_csv(
        "https://world.openfoodfacts.org/data/packagings.packagings-with-weights.csv",
        delimiter="\t",
        dtype={"categories_tags": str, "code": str},
    )
    # Don't keep elements with unknown categories
    df = df.drop(df.categories_tags[df.categories_tags.isnull()].index)

    # Fetch weight specified by the producer first and fallback on user measured weight otherwise
    df["weight"] = [
        (weight_specified if not math.isnan(weight_specified) else weight_measured)
        for (weight_specified, weight_measured) in zip(
            df.weight_specified, df.weight_measured
        )
    ]

    if drop_uncomplete:
        # Drop incomplete products, that don't have weights or number of units for all elements
        df["missing_data"] = np.isnan(df.number_of_units) | np.isnan(df.weight)
        missing_data_group_by = (
            df.loc[:, ["code", "missing_data"]].groupby("code").any()
        )
        df["missing_data"] = missing_data_group_by.loc[
            df.code.values, "missing_data"
        ].values
        df = df.drop(df.missing_data[df.missing_data].index).drop(
            "missing_data", axis=1
        )
    else:
        df = df.drop(df.number_of_units[np.isnan(df.number_of_units)].index)

    # We compute the packaging weight per 100g of product
    df["weight_per_100g_of_product"] = df.weight * 100 / df.product_quantity
    # We don't need weight_measured and weight_specified anymore
    df.drop(["weight_measured", "weight_specified"], axis="columns")

    # weight_all_units is the combined weight of all units of this element
    df["weight_all_units"] = df.weight * df.number_of_units
    # This is used to find the main element of the product (the one with the largest weight)
    max_group_by = (
        df.loc[:, ["code", "weight_all_units"]]
        .groupby("code")
        .max()
        # Max over a a group of NaN produces NaN, replace by -1 to prevent setting
        # as main element an element with NaN weight
        .fillna(-1)
    )
    max_weight = max_group_by.loc[df.code.values, "weight_all_units"].values
    df["is_main_component"] = df.weight_all_units == max_weight
    sum_group_by = df.loc[:, ["code", "weight_all_units"]].groupby("code").sum()
    df["percent_total_weight"] = (
        df.weight_all_units
        * 100
        / sum_group_by.loc[df.code.values, "weight_all_units"].values
    )
    return df


def reset_plotting_context():
    sns.set_context("paper", font_scale=0.8)


def display_ratio_charts(
    df: pd.DataFrame, group_name: str = "parent_material", display_by_row: bool = False
):
    df_with_weight_ratio = df[~df.weight_per_100g_of_product.isnull()]
    st.markdown(f"{len(df_with_weight_ratio)} products.")
    order = df_with_weight_ratio[group_name].value_counts().index
    hue_order = df_with_weight_ratio["shape"].value_counts().index
    kwargs = (
        {"row": group_name, "row_order": order, "sharex": False}
        if display_by_row
        else {"col": group_name, "col_order": order}
    )
    with sns.plotting_context("paper", font_scale=0.6):
        g = sns.FacetGrid(
            df_with_weight_ratio, hue="shape", hue_order=hue_order, **kwargs
        )
        g.map(sns.swarmplot, "weight_per_100g_of_product", size=2.5, alpha=0.7)
        axes = [ax[0] for ax in g.axes] if display_by_row else g.axes[0]
        for ax, plot_name in zip(axes, order):
            sns.violinplot(
                data=df_with_weight_ratio[
                    df_with_weight_ratio[group_name] == plot_name
                ],
                x="weight_per_100g_of_product",
                color=".9",
                inner=None,
                ax=ax,
            )
            ax.set_xlabel(None)
            ax.xaxis.set_major_formatter(lambda x, pos: f"{x:.2f} g")
        g.add_legend()
    return g


def display_charts(df, target_category):
    st.markdown(
        """---

In this analysis, we drop all packaging elements with an unknown number of units."""
    )
    filtered_df = df.loc[df.categories_tags.str.contains(target_category).values, :]

    if len(filtered_df) == 0:
        st.markdown("No items")
        return

    main_component_df = filtered_df.loc[df.is_main_component, :]

    st.markdown(
        """The graph below shows the distribution of the total packaging weight, 
by summing the weights of all packaging components (the number of units is taken into account)."""
    )

    sns.set_theme()
    reset_plotting_context()

    fig = plt.figure()
    ax = fig.add_subplot(1, 1, 1)
    weight_sum_df = filtered_df.loc[:, ["code", "weight"]].groupby("code").sum()
    ax = sns.histplot(weight_sum_df, x="weight", ax=ax)
    ax.set(
        xlabel=f"Packaging weight (all elements) [n={len(weight_sum_df)}]",
        ylabel="Count",
    )
    st.pyplot(fig, clear_figure=True)

    st.markdown(
        """## Main packaging element

The main element is the packaging element with the largest weight, obtained 
by multiplying the element weight by the number of units."""
    )
    st.markdown(f"{len(main_component_df.code.unique())} products.")

    shape_count_df = (
        main_component_df.loc[:, ["code", "shape"]]
        .groupby("shape", as_index=False)
        .count()
        .sort_values("code", ascending=False)
        .rename({"code": "count"}, axis="columns")
    )
    shape_count_df["percent"] = (
        shape_count_df["count"] * 100 / shape_count_df["count"].sum()
    )
    fig = plt.figure()
    ax = fig.add_subplot(1, 1, 1)
    sns.barplot(
        data=shape_count_df, y="shape", x="percent", palette="pastel", orient="h", ax=ax
    )
    ax.bar_label(ax.containers[0], labels=shape_count_df["count"], label_type="center")
    ax.set(xlabel="Percentage of main elements with shape (%)", ylabel="Shape")
    st.pyplot(fig=fig, clear_figure=True)

    material_count_df = (
        main_component_df.loc[:, ["code", "parent_material"]]
        .groupby("parent_material", as_index=False)
        .count()
        .sort_values("code", ascending=False)
        .rename({"code": "count"}, axis="columns")
    )
    material_count_df["percent"] = (
        material_count_df["count"] * 100 / shape_count_df["count"].sum()
    )
    fig = plt.figure()
    ax = fig.add_subplot(1, 1, 1)
    sns.barplot(
        data=material_count_df,
        ax=ax,
        y="parent_material",
        x="percent",
        palette="pastel",
        orient="h",
    )
    ax.bar_label(
        ax.containers[0], labels=material_count_df["count"], label_type="center"
    )
    ax.set(xlabel="Percentage of main elements with material (%)", ylabel="Material")
    st.pyplot(fig=fig, clear_figure=True)

    fig = plt.figure()
    ax = fig.add_subplot(1, 1, 1)
    sns.violinplot(
        data=main_component_df,
        y="parent_material",
        x="weight",
        ax=ax,
        inner=None,
        orient="h",
        color="k",
    )
    sns.swarmplot(
        data=main_component_df,
        y="parent_material",
        x="weight",
        ax=ax,
        palette="colorblind",
        hue="shape",
    )
    ax.set_xlabel("Main element weight - one unit (g)")
    ax.set_ylabel("Material")
    st.pyplot(fig=fig, clear_figure=True)

    st.markdown(
        """### Weight of the main packaging element per 100g of product

We divide the weight of the main packaging element with the product weight 
and multiply it by 100, to get the weight per 100 g of product.

We ignore in this analysis products without product weight."""
    )
    g = display_ratio_charts(main_component_df, display_by_row=True)
    st.pyplot(fig=g.figure, clear_figure=True)

    if (main_component_df.parent_material == "en:plastic").any():
        plastic_df = main_component_df[
            main_component_df.parent_material == "en:plastic"
        ]
        st.markdown(
            """## Plastic-specific analysis
This product category contains main elements with plastic, so we display an analysis of the type of plastic of the main element."""
        )

        fig = plt.figure()
        ax = fig.add_subplot(1, 1, 1)
        sns.violinplot(
            data=plastic_df,
            y="material",
            x="weight",
            ax=ax,
            inner=None,
            orient="h",
            color="k",
        )
        sns.swarmplot(
            data=plastic_df,
            y="material",
            x="weight",
            ax=ax,
            palette="colorblind",
            hue="shape",
        )
        ax.set_xlabel("Main element weight (plastic only) - one unit (g)")
        ax.set_ylabel("Plastic material")
        sns.move_legend(ax, "upper left", bbox_to_anchor=(1, 1))
        st.pyplot(fig=fig, clear_figure=True)

        st.markdown("### Weight of the main packaging element per 100g of product")
        g = display_ratio_charts(plastic_df, group_name="material", display_by_row=True)
        st.pyplot(fig=g.figure, clear_figure=True)

    fig = plt.figure()
    ax = fig.add_subplot(1, 1, 1)
    sns.swarmplot(
        data=main_component_df,
        y="parent_material",
        x="percent_total_weight",
        palette="colorblind",
        hue="shape",
        ax=ax,
    )
    sns.move_legend(ax, "upper left", bbox_to_anchor=(1, 1))
    ax.set(xlabel="Percent of total packaging weight (%)", ylabel="Material")
    st.pyplot(fig=fig, clear_figure=True)

    st.markdown("## Number of packaging elements")
    total_num_units_df = (
        filtered_df.loc[:, ["code", "number_of_units"]].groupby("code").sum()
    )
    fig = plt.figure()
    ax = fig.add_subplot(1, 1, 1)
    sns.histplot(total_num_units_df, x="number_of_units", ax=ax)
    ax.set(
        xlabel="Distribution of the total number of packaging elements", ylabel="Count"
    )
    st.pyplot(fig=fig, clear_figure=True)

    with st.expander("Show data"):
        st.markdown("Weight sum dataframe")
        st.write(weight_sum_df)
        st.markdown(f"Dataframe: category={target_category}")
        st.write(filtered_df.loc[:, COLUMN_DISPLAY])
        st.markdown("Number of units dataframe")
        st.write(total_num_units_df)


st.title("Packaging analysis")
st.markdown(
    """You can explore the Open Food Facts packaging data using this demo. 
Start by providing a category to analyze."""
)

category_names = get_category_names()
category_ids = list(category_names.keys())

category = st.selectbox(
    "Category",
    options=category_ids,
    format_func=lambda x: category_names[x],
    help="Category to analyze",
    index=category_ids.index("en:yogurts"),
)
drop_uncomplete = st.checkbox(
    "Drop uncomplete",
    value=True,
    help="Drop all products that don't have complete packaging "
    "(i.e weight and number of units for all elements)",
)
df = get_base_df(drop_uncomplete=drop_uncomplete)
display_charts(df, category)