sorting a String array?

Programming Questions

scientiff..

in Programming Questions • 1 year ago

I am trying to sort a string array and am not getting the right order:

String[] a = { "1.105", "23.805", "29.31", "53.6", "105.217", "10.896307" };
a = sort(a);
println(a);

is returning:

{1.105, 10.896307, 105.217, 23.805, 29.31, 53.6}

I am using a string array rather than a float array since I'm using loadStrings to load values from a text file.

Replies(5)

jbum

Re: sorting a String array?

1 year ago

Because they are strings, it is doing a lexical sort, rather than a numeric sort. If you want them treated as numbers, then convert them into an array of numbers after you load them in. Like so:

String[] a = { "1.105", "23.805", "29.31", "53.6", "105.217", "10.896307" };

float[] b = new float[a.length];

for (int i = 0; i < a.length; ++i)

b[i] = Float.parseFloat(a[i]);

b = sort(b);

println(b);

Alternately, you can supply a comparator to the sort routine that does the right thing with the strings; but that seems like overkill, considering you actually wanted numbers in the first place.

PhiLho

Re: sorting a String array?

1 year ago

Simpler:
float[] b = float(a);
b = sort(b);
println(b);

jbum

Re: sorting a String array?

1 year ago

Woah, I've never seen that kind of array type coercion... Awesome.

PhiLho

Re: sorting a String array?

1 year ago

It is part of the magic of Processing, the pre-processor allowing to use a Java keyword (float or int) as function name... After pre-processing, it is replaced by parseFloat (resp. parseInt).

scientiff..

Re: sorting a String array?

1 year ago

awesome, thanks!!

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