array formatting

[tester]

How to format array of floats using ruby?
Equivalent of "format string" primitive.
For example trim array values to 0.00 or set display like 000.00 and so on.

[trogluddite]

Equivalent of "format string" primitive...

...is the 'format' method. It uses exactly the same format codes as the primitive - which you give as the first argument (in the form of a string), followed by the value that needs formatting... e.g.

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@x = Math::PI
format( "%.3f", @x)   #=>  "3.142"

You can include more than just the '%' codes too...

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format("The value of PI is %.3f approximately", @x)  #=> "The value of PI is 3.142 approximately"

Or include multiple '%' codes and a list of substitute items to match...

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@x = 5.12345
@y = @x * @x
format("The square of %.3f is %.3f", @x, @y)   #=>  "The square of 5.123 is 26.250"

To do this for every item in the array, the method "collect" is the easiest way - or you can call it "map" if you're not so keen on typing! It takes every item in an array, processes it, and then places all the answers in a new array...

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@myArray = [1, 2, 3, 4, 5]
@format_code = "%.3f"
@formatted = @myArray.collect{|item|  format(@format_code, item)}

Here's a module based on that code that spits out both a string array and a single string of joined items...

Float Array Format.fsm

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PS) There's a full list of the supported format codes HERE.