Statistics function

Question

I have created a database using Django. I have a small statistics page as shown below. Can I improve this code?

View file

def statistics(request):
        """ Return the number of categories (Category is based on first 
        three-letter character, say Cry in the example) in the database 
        and its corresponding count.

        The holotype is a protein name that ends in 1. Example: Cry1Aa1
        A holotype is a single protein name used to name the lower rank based on identity. 
        Cry1Aa2 is named based on the identity to Cry1Aa1
        """
    category_count = {}
    category_holotype_count = {}
    category_prefixes = []
    total_holotype = 0

    categories = \
        PesticidalProteinDatabase.objects.order_by(
            'name').values_list('name', flat=True).distinct()
    for category in categories:
        cat = category[:3]
        if category[-1] == '1' and not category[-2].isdigit():
            total_holotype += 1
            count = category_holotype_count.get(cat, 0)
            count += 1
            category_holotype_count[cat] = count

    category_count['Holotype'] = [total_holotype] * 2

    for category in categories:
        prefix = category[0:3]
        if prefix not in category_prefixes:
            category_prefixes.append(prefix)

    for category in category_prefixes:
        count = PesticidalProteinDatabase.objects.filter(
            name__istartswith=category).count()
        category_count[category] = [
            count, category_holotype_count.get(category, 0)]

    prefix_count_dictionary = {}
    for prefix in category_prefixes:
        prefix_count_dictionary[prefix] = category_count[prefix][0]

    prefix_count_dictionary.pop('Holotype', None)

    context = \
        {'category_prefixes': category_prefixes,
         'category_count': category_count}

    return render(request, 'database/statistics.html', context)

Urls file

    path('statistics/', views.statistics,
         name='statistics'),

Sample HTML file

<b>General Statistics</b>

        <table class="table table-bordered table-hover">
            <thead>
                <tr>
                    <th>No</th>
                    <th>Category</th>
                    <th>Total Count</th>
                    <th>Holotype Count</th>
                </tr>

           {% for key,value in category_count.items %}

                    <tr>
                        <td> {{ forloop.counter }} </td>
                        <td> {{ key }} </td>
                        <td> {{ value.0 }} </td>
                        <td> {{ value.1 }} </td>
                    </tr>
           {% endfor %}
            <thead>
        <table>

Answer 1

The first for loop can be simplified a lot by using collections.Counter. The generation of the distinct category_prefixes using a set and the final category_count dictionary using a dictionary comprehension:

db = PesticidalProteinDatabase
categories = db.objects.order_by('name').values_list('name', flat=True).distinct()
holotype_counts = Counter(category[:3] for category in categories
                          if category[-1] == '1' and not category[-2].isdigit())

category_prefixes = sorted({category[:3] for category in categories})
category_count = {cat: [db.objects.filter(name__istartswith=cat).count(), 
                        holotype_counts[cat]]
                  for cat in category_prefixes}
category_count['Holotype'] = [sum(holotype_counts.values())] * 2

Note that PesticidalProteinDatabase is not a name following Python's official style-guide, PEP8, which recommends using lower_case for variables and functions and PascalCase only for classes (not instances of classes).