Using Select with arrays? (Relative newbie)

• To: mathgroup at smc.vnet.net
• Subject: [mg54216] Using Select with arrays? (Relative newbie)
• From: Hugo Mallinson <hfm21 at cam.ac.uk>
• Date: Sun, 13 Feb 2005 22:17:04 -0500 (EST)
• Organization: University of Cambridge, England
• Sender: owner-wri-mathgroup at wolfram.com

```The subject might not be entirely correct, but here is my problem:

I have a list of 5-variable data points like

data = {
{1, 1, string1, c, d}
{1, 2, string2, c, d}
{1, 3, string3, c, d}
{1, 4, string4, c, d}
{2, 1, string1, c, d}
{2, 2, string2, c, d}
{3, 1, string3, c, d}
{4, 1, string2, c, d}
{4, 2, string4, c, d}
}

and I want to extract just the points that have 1 (or 2, etc) as their
first value. I think I should do something like

Select[data, {1, _Integer, _String, _Integer, _Integer}]

but that doesn't work.

Having done that I need to find the maximum value of #2 for each
string, which I presumably do by the same method as above to extract
all string1 (or ...2) and then use Map[] and Max[]. I would do this all
with For loops (revealing my lack of Mathematica chops :-) ) but I'd
really like to learn how to do this sort of extraction in a
Mathematica-y way. Any help would be greatly appreciated!

Hugo

```

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