Re: trimming a string
- To: mathgroup at smc.vnet.net
- Subject: [mg50891] Re: [mg50861] trimming a string
- From: Murray Eisenberg <murray at math.umass.edu>
- Date: Sun, 26 Sep 2004 05:31:56 -0400 (EDT)
- Organization: Mathematics & Statistics, Univ. of Mass./Amherst
- References: <200409240841.EAA21787@smc.vnet.net>
- Reply-to: murray at math.umass.edu
- Sender: owner-wri-mathgroup at wolfram.com
I don't know whether this should be considered "simple", but here's an
interesting array-oriented way:
(* begin code *)
nonBlankQ[txt_] := (# ? " ") & /@ txt
foldIt[op_, lis_] := FoldList[op, First @ lis, Rest @ lis]
logicalSelect[v_List, b_List] :=
Cases[Thread[{v, b}], {val_, True} :> val]
DeleteLeadingTrailingBlanks[s_String] := Module[
{chars = Characters[s],
notBlank, notLeading, notTrailing, neither},
notBlank = nonBlankQ[chars];
notLeading = foldIt[Or, notBlank];
notTrailing = Reverse @ foldIt[Or, Reverse @ notBlank];
neither = Apply[And, #] & /@ Transpose[{notLeading, notTrailing}];
StringJoin @ logicalSelect[chars, neither]
]
(* example *)
s = " he l lo ";
DeleteLeadingTrailingBlanks[s]
StringLength[%]
(* end code *)
This is a translation of a rather old "idiom" from Ken Iverson's APL
array-oriented language. Expressed in Iverson's sequel J (see
www.jsoftwarse.com) to APL, it takes the particulary terse form:
dltb=: #~ [: (+./\ *. +./\.) ' '&~:
NB. For example (input is indented, output flush left):
dltb ' he l lo '
he l lo
# dltb ' he l lo '
8
Akos Beleznay wrote:
> I would appreciate if somebody could show me a simple way of trimming a
> string. (I did it a hard way, but suspect an elegant solution.)
>
> Trim(a_string): returns a copy of a string without leading and trailing
> spaces.
>
> thanks for your help,
>
> Akos Beleznay
> Equitas Capital Advisors LLC
> 909 Poydras Street
> Suite 1850
> New Orleans, LA 70112
> Phone: (504) 569-9607
> Fax: (504) 569-9650
> abeleznay at equitas-capital.com
>
>
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--
Murray Eisenberg murray at math.umass.edu
Mathematics & Statistics Dept.
Lederle Graduate Research Tower phone 413 549-1020 (H)
University of Massachusetts 413 545-2859 (W)
710 North Pleasant Street fax 413 545-1801
Amherst, MA 01003-9305
- References:
- trimming a string
- From: "Akos Beleznay" <abeleznay@equitas-capital.com>
- trimming a string