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>

Display page

• Reinderien: Please show more of your code, including what produces request.

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).