       Re: Count Function

• To: mathgroup at smc.vnet.net
• Subject: [mg65526] Re: Count Function
• From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
• Date: Thu, 6 Apr 2006 06:52:31 -0400 (EDT)
• Organization: The Open University, Milton Keynes, UK
• References: <e1091t\$ljd\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Gregory Lypny wrote:
> The syntax will be the death of me.
>
> Count[X[[All,14]], -9.] will tally how many elements in column 14 of
> matrix X are equal to -9, but I can't for the life of me figure out
> how to get how many are greater than -9.  Any hint would be most
> appreciated.
>
> 	Greg
>
>
Hi Greg,

Here is an example with a 20 by 2 matrix:

In:=
data = Table[{n, Random[Integer, {1, 15}]}, {n, 20}]

Out=
{{1, 15}, {2, 10}, {3, 15}, {4, 5}, {5, 8}, {6, 13},
{7, 4}, {8, 3}, {9, 1}, {10, 3}, {11, 6}, {12, 10},
{13, 2}, {14, 15}, {15, 13}, {16, 4}, {17, 1},
{18, 4}, {19, 9}, {20, 12}}

In:=
Count[data[[All,2]], _?(#1 > 9 & )]

Out=
8

Hope this helps,
Jean-Marc

```

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