diff options
Diffstat (limited to 'array.c')
-rw-r--r-- | array.c | 45 |
1 files changed, 36 insertions, 9 deletions
@@ -2998,21 +2998,48 @@ 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(VALUE ary) +rb_ary_sample(int argc, VALUE *argv, VALUE ary) { - long i, j; + VALUE nv, result; + int n, len, i, j; - i = RARRAY_LEN(ary); - if (i == 0) return Qnil; - j = rb_genrand_real()*i; - return RARRAY_PTR(ary)[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; + ARY_SET_LEN(result, i+1); + } + for (i=0; i<n; i++) { + nv = RARRAY_PTR(result)[i]; + RARRAY_PTR(result)[i] = RARRAY_PTR(ary)[NUM2LONG(nv)]; + } + return result; } @@ -3526,7 +3553,7 @@ Init_Array(void) 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); |