2.py

acc_category = data[["category"]]
acc_category = acc_category.drop_duplicates()
acc_category = acc_category.reset_index(drop=True)
acc_category["id"] = acc_category.index

# relate tables with index
for i, row in data.iterrows():
    cat = data.at[i, "category"]

    for j, row in acc_category.iterrows():
        if acc_category.at[j, "category"] == cat:
            cat_id = acc_category.at[j, "id"]
            data.at[i, "category_id"] = cat_id

data = data.drop(columns="category")
data = data.astype({"category_id":int, "num_injured":int}, errors="raise")