Method `Single::frequencies()` added

[Smoren]

Hi @markrogoyski,

This is a draft of PR. If you like my implementation, I'll finish it.

BTW I think this method is more suitable for Single namespace, not for Reduce (as you suggest) because it returns a generator.

[coveralls]

Pull Request Test Coverage Report for Build 4465593691

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Details

• 15 of 15 (100.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.002%) to 99.873%

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Totals
Change from base Build 4462214447:	0.002%
Covered Lines:	787
Relevant Lines:	788

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💛 - Coveralls

[Smoren]

Hi @markrogoyski, thank you, I used zipEqual() as you suggested.

Also I added Stream::frequencies() method and covered it with test.

BTW, I what do you think about a new namespace like Stat for this function? Or maybe use Math?

[markrogoyski]

Hi @Smoren,

Thank you for this pull request, and apologies at the delay at reviewing it.

I have a suggestion, let's create two functions, using the technical definitions:

• frequencies which will return the number of times an item occurs. See frequency definition.
• relativeFrequencies which will return the ratio of the frequency against the total count (Which is what you have implemented already). See relative frequency defintion

For reference, this is also the same terminology used in MathPHP.

use MathPHP\Statistics\Distribution;

$grades = ['A', 'A', 'B', 'B', 'B', 'B', 'C', 'C', 'D', 'F'];

// Frequency distributions (frequency and relative frequency)
$frequencies          = Distribution::frequency($grades);         // [ A => 2,   B => 4,   C => 2,   D => 1,   F => 1   ]
$relative_frequencies = Distribution::relativeFrequency($grades); // [ A => 0.2, B => 0.4, C => 0.2, D => 0.1, F => 0.1 ]

Thoughts about this change? Thanks, Mark

[Smoren]

Hi @markrogoyski,

Your suggestion is implemented!

[markrogoyski]

Hi @Smoren,

Thanks for implementing the change. Looks good to me.

Mark

[Smoren]

Thank you @markrogoyski!

[markrogoyski]

Hi @Smoren,

Considering one of your earlier comments a bit more, I moved this functionality into the Math namespace. It seems a better fit there.

Thanks again, Mark

[Smoren]

Thank you @markrogoyski!