Difficulty with patterns
- To: mathgroup at smc.vnet.net
- Subject: [mg122281] Difficulty with patterns
- From: "McHale, Paul" <Paul.McHale at excelitas.com>
- Date: Sun, 23 Oct 2011 06:24:34 -0400 (EDT)
- Delivered-to: l-mathgroup@mail-archive0.wolfram.com
I have recently become increasingly uncomfortable with my areas of ignorance with Mathematica. The Virtual conference has some really cool demos. In one, a website is read in and a table of data extracted. Without patterns, it would have been very difficult. Need a little help with an example.
Example 1 uses my old standby, the Table[] function. Works fine. I am attempting to get better with patterns, so I tried example 2 and 3. They work, but gives several errors about use of stringjoin needing strings. What am I doing wrong?
Error: StringJoin::string: String expected at position 1 in StringJoin[n].
(* Load string from WolframAlpha *)
m WolframAlpha["usa",{{"LargestCities:CountryData",1},"ComputableData"},
PodStates->{"LargestCities:CountryData__More","LargestCities:CountryData__More"}];
(* example 1 *)
mNew=Flatten[m,1];
mNew=Drop[mNew,1];
mNew=Drop[mNew,-1];
mNew=Table[{i[[1,1]] <> i[[1,2]] <> i[[1,2]] ,i[[2]]},{i,mNew}];
Grid[mNew,Frame->All]
(* example 2 *)
Clear[n,o,p,q];
mNew=Cases[m, {{n_String,o_String,p_String},q_} -> { n <> ", " <> o <> ", " <> p,q},Infinity ];
Grid[mNew,Frame->All]
(* example 3 *)
Clear[n,o,p,q];
mNew=Cases[m, {{n_,o_,p_},q_} -> { n , ", ", o , ", ", p,q},Infinity ];
mNew = mNew /. {n___,q_Integer} -> {StringJoin[n],q};
Grid[mNew,Frame->All]
I even tried,
mNew = Flatten[m, 1];
mNew = Drop[mNew, 1];
mNew = Drop[mNew, -1];
mNew = Table[{Head[i[[1, 1]]], Head[i[[1, 2]]], Head[ i[[1, 2]]] ,
i[[2]]}, {i, mNew}];
(*mNew=Table[{i[[1,1]] <> i[[1,2]] <> i[[1,2]] ,i[[2]]},{i,mNew}];*)
Grid[mNew, Frame -> All]
They are all strings!
Thanks,
Paul
Paul McHale | Electrical Engineer, Energetics Systems | Excelitas Technologies Corp.
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Phone: +1 937.865.3004 | Fax: +1 937.865.5170 | Mobile: +1 937.371.2828
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Paul.McHale at Excelitas.com
www.excelitas.com
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