A csv file has two column CATEGORY and MILES, I have to find % of Miles under Business Category and % of Miles under Personal Category, in python - python-3.x

Question

CATEGORY MILES
Business 5.1
Business 4.6
Business 3.9
Personal 8.5
Business 3.7
Personal 6.2
Personal 11
This is an excerpt from the excel sheet

Answer 1

So you have a text file in CSV format, and you need to read it, convert it into combinations of [Category, Miles], and you want for every Category "% of miles", whatever that may be.
Category Miles
X 1
X 4
X 2
Y 3
I think that you want: "Category X has 70% of the miles, Category Y also has 30% of the miles".
To solve this, it is best to cut your problem into smaller pieces.
Given a string fileName, read the file as text
Given a string in CSV format, convert it into a sequence of class BusinessMiles
Given a sequence of BusinessMiles, convert it to "% of miles", according to the definition above.
Cutting your problem into smaller pieces has several advantages:
The function of each piece will be easier to understand
Easier to unit test.
Easier to change, for instance if you don't read from a CSV file, but from a database, or if you don't read from a CSV string, but from an XML or JSON file.
Most important: you will be able to reuse the pieces for other tasks, like: "How many of my rows are about Business?"
The reusability is demonstrated most clearly, because several of these pieces already exist and can be used freely: reading the file and converting the file to CSV.
For this, consider to use Nuget Package CSV helper. Easy to use, versatile, and thus one of the most used CSV packages.
So let's assume you have procedures to read the CSV file and to convert it to a sequence of BusinessMiles
enum Category
{
Business,
Personal,
}
class BusinessMile // TODO: invent proper name
{
public Category Category {get; set;}
public Decimal Miles {get; set;}
}
By using an enum you can be certain that after reading the CSV there won't be any incorrect Categories. It will be easy to add new Categories for a future version. If you don't know at compile time which Categories are allowed, consider to use a string for it. This has the danger that someone might have a typing error, which leads to a complete new Category, without anyone noticing "Personnel" instead of "Personal"
IEnumerable<BusinessMile> ReadBusinessMiles(string csvText)
{
// use CSVHelper to convert the csvText to the sequence
}
IEnumerable<BusinessMile> ReadBusineMilesFile(string fileName)
{
// either use CSVHelper, or read the file and call the other method
}
After this, your problem will be easy:
string fileName = ...
IEnumerable<BusinessMile> businessMiles = ReadBusinesMilesFile(fileName);
Make groups of BusinessMiles that have the same Category:
var categoryGroups = businessMiles.GroupBy(
businessMile => businessMile.Category,
// parameter resultSelector: for every Category, and all BusinessMiles
// that have this Category to make one new
(category, businessMilesInThisCategory) => new
{
Category = category,
TotalMiles = businesMilesInThisCategory
.Select(businessMile => businessMile.Miles)
.Sum(),
});
So now you've got:
Category TotalMiles
X 7
Y 3
If you really want to have percentages, you need to get the total of all Miles of all Categories (=6), and divide TotalMiles by this total
var totalMiles = categorieGroups.Select(group => group.TotalMiles).Sum();
var result = categoryGroups.Select(group => new
{
Category = group.Category,
TotalMilesPercentage = 100.0M * group.TotalMiles / totalMiles,
})
In my definition of BusinessMiles, the Miles are a decimal. Take care to convert it if your Miles are integers.