Re: Creating List
- To: mathgroup at smc.vnet.net
- Subject: [mg125535] Re: Creating List
- From: Bill Rowe <readnews at sbcglobal.net>
- Date: Sun, 18 Mar 2012 02:40:24 -0500 (EST)
- Delivered-to: l-mathgroup@mail-archive0.wolfram.com
On 3/17/12 at 2:51 AM, hvdosten at gmail.com (Harry) wrote:
>I have calculated some x- and y-values and want to combine them in a
>way that the x and y-values define coordinates. Well, I have:
>xkoor[i], {i, 1, iend} and ykoor[j], {j, 1, jend}
>To be able to continue I need this list:
>{{xkoor[1],ykoor[1]},
>{xkoor[2],ykoor[1]}, {xkoor[3],ykoor[1]}, {xkoor[4],ykoor[1]},
>{xkoor[1],ykoor[2]}, {xkoor[2],ykoor[2]}, {xkoor[3],ykoor[2]},
>{xkoor[4],ykoor[2]}, {xkoor[1],ykoor[3]}, {xkoor[2],ykoor[3]},
>{xkoor[3],ykoor[3]}, {xkoor[4],ykoor[3]}}
>and have no idea how to get this. So I would be very happy to get
>any small hint...
Here is something to consider:
In[13]:= x = Range[4];
y = Range[5, 15, 5];
In[15]:= Join @@ ((Join @@ Outer[List, x, {#}]) & /@ y)
Out[15]= {{1, 5}, {2, 5}, {3, 5}, {4, 5}, {1, 10}, {2, 10}, {3,
10}, {4, 10}, {1, 15}, {2, 15}, {3, 15}, {4, 15}}
But do note, this code creates a 2-D list, i.e., a list of lists not what you showed in your post.
I can generate the output you posted with:
In[18]:= Join @@ ((Join @@
Outer[{xkoor[#1], ykoor[#2]} &, Range[4], {#}]) & /@ Range[3])
Out[18]= {{xkoor[1], ykoor[1]}, {xkoor[2], ykoor[1]}, {xkoor[3],
ykoor[1]}, {xkoor[4], ykoor[1]}, {xkoor[1], ykoor[2]}, {xkoor[2],
ykoor[2]}, {xkoor[3], ykoor[2]}, {xkoor[4], ykoor[2]}, {xkoor[1],
ykoor[3]}, {xkoor[2], ykoor[3]}, {xkoor[3], ykoor[3]}, {xkoor[4],
ykoor[3]}}