Re: Counting Elements in a List
- To: mathgroup at smc.vnet.net
- Subject: [mg27967] Re: [mg27959] Counting Elements in a List
- From: BobHanlon at aol.com
- Date: Tue, 27 Mar 2001 01:26:05 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
mylist = {{1, 2, 3, 4}, {1, 2, 3, 5}, {1, 3, 4, 6}, {1, 3, 6, 9}, {2, 4, 7,
8}};
Length[Select[mylist, #[[4]] >= 8 &]]
2
Count[mylist, _?(#[[4]] >= 8&)]
2
Count[mylist, x_ /; x[[4]] >= 8]
2
Bob Hanlon
In a message dated 2001/3/26 5:49:23 AM, JOHN_C_ERB at prodigy.net writes:
>I have a list in which I want to count the number of times the 4th element
>(i.e., 4th column) meets certain specifications (e.g., where it greater
>than
>or equal to 8).
>
>I can do this by:
>
>mylist = {{1, 2, 3, 4}, {1, 2, 3, 5}, {1, 3, 4, 6}, {1, 3, 6, 9}, {2, 4,
>7,
>8}};
>Length[Select[mylist, #[[4]] >= 8 &]]
>
>Surely, there is another, more direct, way of doing this using Count?
>