Fastest way to convert string array to double array?

Question

I've been having to deal lately with conversion of large string arrays to number arrays and I'm wondering what the fastest method out there for this really is.

At first I adopted:

double[] doubles = sarray.Split(',').Select(Double.Parse).ToArray();

...which is really sweet... But today, I decided to switch back to a simple for loop to parse all strings in array to Double and not too surprisingly the benchmark seemed to favour the for loop.. so should I switch back to a basic for loop?

Also, I want to know if there's a better type that can be used to store the splitted strings e.g. HashSet which may perform better during this conversion?

The title says int but in the code you are using double. Which is it? — cadrell0, Mar 01 '12 at 21:56
sorry, I don't know if it's only me but I have this problem of thinking of numbers as *int. :) — Chibueze Opata, Mar 01 '12 at 21:59

score 50 · Accepted Answer · answered Mar 01 '12 at 21:51

50

Array.ConvertAll(sarray.Split(','), Double.Parse);

Unlike LINQ's .ToArray(), this pre-allocates a correctly-sized array and doesn't do any resizing.
This should be indistinguishable from a hand-rolled loop.

answered Mar 01 '12 at 21:51

SLaks

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Would this be faster than the `for` loop? – M.Babcock Mar 01 '12 at 21:54
2

Wow! I always forget about the Array class! That was awesome. Thanks!! – Chibueze Opata Mar 01 '12 at 21:55

score 14 · Answer 2 · answered Feb 28 '13 at 01:39

When I used:

double[] doubles = Array.ConvertAll(sarray.split(','), Double.Parse);

I got this error:

The type arguments for method 'System.Array.ConvertAll(TInput[], System.Converter)' cannot be inferred from the usage. Try specifying the type arguments explicitly.

But it worked when I did this:

double[] doubles = Array.ConvertAll(sarray.split(','), new Converter<string, double>(Double.Parse));

Fastest way to convert string array to double array?

2 Answers2

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