MathGroup Archive 2012

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Intersection problem

  • To: mathgroup at
  • Subject: [mg125985] Re: Intersection problem
  • From: Adriano Pascoletti <adriano.pascoletti at>
  • Date: Wed, 11 Apr 2012 18:19:05 -0400 (EDT)
  • Delivered-to:
  • References: <>

Three solutions

In[1]:= Select[{{a, x}, {b, y}, {c, z}}, MemberQ[{b, c, d}, #1[[1]]] & ]
Out[1]= {{b, y}, {c, z}}
In[2]:= Cases[{{a, x}, {b, y}, {c, z}}, {i_, _} /; MemberQ[{b, c, d}, i]]
Out[2]= {{b, y}, {c, z}}
In[3]:= Cases[{{a, x}, {b, y}, {c, z}}, {Alternatives @@ {b, c, d}, _}]
Out[3]= {{b, y}, {c, z}}

Adriano Pascoletti

2012/4/10 Cisco Lane <travlorf at>

> I need to select out the elements of the first list whose first elements
> are contained in the second list. For example
> first list: {{a,x},{b,y},{c,z}}
> second list: {b,c,d}
> result: {{b,y},{c,z}}
> Is there a quick way to do this? Intersection, maybe somehow?

  • Prev by Date: HostMath - Generate and embed math equations or mathematical formulas in a blog or website
  • Next by Date: Re: Intersection problem
  • Previous by thread: Re: Intersection problem
  • Next by thread: Re: Intersection problem