diff options
| author | matz <matz@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2008-08-12 05:08:52 +0000 |
|---|---|---|
| committer | matz <matz@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2008-08-12 05:08:52 +0000 |
| commit | e65c07e98b1b076ab99a2b12043148b3b4962386 (patch) | |
| tree | 66825c27aa6002a3ef252c9aee08417dcbff17f8 /array.c | |
| parent | aadf534bb33a9698cf1521afe675a7a90d0becff (diff) | |
* array.c (rb_ary_sample): rename #choice to #sample. in
addition, sample takes optional argument, a la #first.
* random.c (Init_Random): always initialize seed.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_8@18509 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Diffstat (limited to 'array.c')
| -rw-r--r-- | array.c | 47 |
1 files changed, 38 insertions, 9 deletions
@@ -3301,22 +3301,51 @@ rb_ary_shuffle(VALUE ary) /* * call-seq: - * array.choice -> obj + * array.sample -> obj + * array.sample(n) -> an_array + * + * Choose a random element, or the random +n+ elements, fron the array. + * If the array is empty, the first form returns <code>nil</code>, and the + * second form returns an empty array. * - * Choose a random element from an array. */ static VALUE -rb_ary_choice(ary) +rb_ary_sample(argc, argv, ary) + int argc; + VALUE *argv; VALUE ary; { - long i, j; + VALUE nv, result; + int n, len, i, j; - i = RARRAY(ary)->len; - if (i == 0) return Qnil; - j = rb_genrand_real()*i; - return RARRAY(ary)->ptr[j]; + len = RARRAY_LEN(ary); + if (argc == 0) { + if (len == 0) return Qnil; + i = rb_genrand_real()*len; + return RARRAY_PTR(ary)[i]; + } + rb_scan_args(argc, argv, "1", &nv); + if (len == 0) return rb_ary_new2(0); + n = NUM2INT(nv); + result = rb_ary_new2(n); + for (i=0; i<n; i++) { + retry: + j = rb_genrand_real()*len; + nv = LONG2NUM(j); + for (j=0; j<i; j++) { + if (RARRAY_PTR(result)[j] == nv) + goto retry; + } + RARRAY_PTR(result)[i] = nv; + RARRAY(result)->len = i+1; + } + for (i=0; i<n; i++) { + nv = RARRAY_PTR(result)[i]; + RARRAY_PTR(result)[i] = RARRAY_PTR(ary)[NUM2LONG(nv)]; + } + return result; } @@ -3852,7 +3881,7 @@ Init_Array() rb_define_method(rb_cArray, "count", rb_ary_count, -1); rb_define_method(rb_cArray, "shuffle!", rb_ary_shuffle_bang, 0); rb_define_method(rb_cArray, "shuffle", rb_ary_shuffle, 0); - rb_define_method(rb_cArray, "choice", rb_ary_choice, 0); + rb_define_method(rb_cArray, "sample", rb_ary_sample, -1); rb_define_method(rb_cArray, "cycle", rb_ary_cycle, -1); rb_define_method(rb_cArray, "permutation", rb_ary_permutation, -1); rb_define_method(rb_cArray, "combination", rb_ary_combination, 1); |