Question

Mathematica 如何取出匹配的元素？

如何取出匹配的元素？
例如; 取出与s2匹配的元素
输入： s1={{a->x,b->y,c->y,d->x,e->z,e->z,g->z,h->w}};
s2={x,w};
输出 s3={a,d,h}
以及任意多层表的元素取出,例如
输入： s1={{a->x,b->y,c->y},{d->x,e->z,e->z,g->z,h->w}}};
s2={x,w};
输出 s3={{a},{d,h}}

Answer 1

提取指定元素的表
例如:
输入; s1={{a,b,x,y,c},{c,d,e,x},{x,a,y,d,z},{z,a,b}}
输出; s2={{a,b,x,y,c},{x,a,y,d,z}}
s3={{a,b,x,y,c},{c,d,e,x},{x,a,y,d,z}}
s4={{c,d,e,x},{z,a,b}}
s5={{z,a,b}}
即: s2------含x与y s3------含x 或y s4------不含x与y s5------不含x 或y
则可如下方式：

s1 = {{a, b, x, y, c}, {c, d, e, x}, {x, a, y, d, z}, {z, a, b}};
s2 = Select[s1, MemberQ[#, x] && MemberQ[#, y] &];
s3 = Select[s1, MemberQ[#, x] || MemberQ[#, y] &];
s4 = Complement[s1, s2];
s5 = Complement[s1, s3];

Answer 2

s1 = {{a -> x, b -> y, c -> y, d -> x, e -> z, e -> z, g -> z, h -> w}};
s2 = {x, w};
s3 = s1 /. Rule[a_, b_] /; MemberQ[s2, b] :> a /. Rule[a_, b_] -> Sequence[]
==> {{a, d, h}}
s4 = {{a -> x, b -> y, c -> y}, {d -> x, e -> z, e -> z, g -> z, h -> w}};
s5 = {x, w};
s6 = s4 /. Rule[a_, b_] /; MemberQ[s5, b] :> a /. Rule[a_, b_] -> Sequence[]
==> {{a}, {d, h}}