Array question
in [Visual Basic]
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From: dpb on 12 Aug 2010 11:17 Henning wrote: > "dpb" <none(a)non.net> skrev i meddelandet .... >> Or, a language that supports array slices (such as Fortran or Matlab)... >> :) >> >> sngTest = sngArr(1,:) % Matlab syntax; Fortran is very similar >> >> -- > > Or use the easy way out. > sngTest(0) = sngArr(1,0) > sngTest(1) = sngArr(1,1) > > If lots of elements. > For i = 0 to NumElements > sngTest(i) = sngArr(1,i) > Next .... Oh, indeed...take the obvious route. What's the fun in that? I was just being kinda' snarky... :) It's been a pet peeve for years of mine that VB w/ all it's user conveniences never implemented array slice notation. It seems such an obvious extension for a language intended for rapid development. --
From: Tom Shelton on 12 Aug 2010 11:43 on 8/12/2010, dpb supposed : > Henning wrote: >> "dpb" <none(a)non.net> skrev i meddelandet > ... > >>> Or, a language that supports array slices (such as Fortran or Matlab)... >>> :) >>> >>> sngTest = sngArr(1,:) % Matlab syntax; Fortran is very similar >>> >>> -- >> >> Or use the easy way out. >> sngTest(0) = sngArr(1,0) >> sngTest(1) = sngArr(1,1) >> >> If lots of elements. >> For i = 0 to NumElements >> sngTest(i) = sngArr(1,i) >> Next > ... > > Oh, indeed...take the obvious route. What's the fun in that? > > I was just being kinda' snarky... :) > > It's been a pet peeve for years of mine that VB w/ all it's user conveniences > never implemented array slice notation. It seems such an obvious extension > for a language intended for rapid development. It's funny, but I can't think of any statically compiled language that implements array slice functionality. It's seem to only be in the dynamic languages - Perl, Python, Ruby, etc..... -- Tom Shelton
From: dpb on 12 Aug 2010 15:02 Tom Shelton wrote: .... > It's funny, but I can't think of any statically compiled language that > implements array slice functionality. It's seem to only be in the > dynamic languages - Perl, Python, Ruby, etc..... Fortran for at least one...requires F90+, but that's now the norm and is 20+ years old now... Some examples; there are many other ways for usage as well... > Array assignment is permitted when the array expression on the right > has the same shape as the array variable on the left, or the expression > on the right is a scalar. > If the expression is a scalar, and the variable is an array, the > scalar value is assigned to every element of the array. > If the expression is an array, the variable must also be an array. > The array element values of the expression are assigned (element by > element) to corresponding elements of the array variable. > > A many-one array section is a vector-valued subscript that has two or > more elements with the same value. In intrinsic assignment, the > has the same shape as the array variable on the left, or the expression > on the right is a scalar. > > Examples > > In the following example, X and Y are arrays of the same shape: > > X = Y > > The corresponding elements of Y are assigned to those of X element by > element; the first element of Y is assigned to the first element of X, > and so forth. The processor can perform the element-by-element > assignment in any order. > > The following example shows a scalar assigned to an array: > > B(C+1:N, C) = 0 > > This sets the elements B (C+1,C), B (C+2,C),...B (N,C) to zero. > > The following example causes the values of the elements of array A to > be reversed: > > REAL A(20) > ... > A(1:20) = A(20:1:-1) > .... > A vector subscript is a one-dimensional (rank one) array of integer > values (within the declared bounds for the dimension) that selects a > section of a whole (parent) array. The elements in the section do not > have to be in order and the section can contain duplicate values. > > For example, A is a rank-two array of shape (4,6). B and C are > rank-one arrays of shape (2) and (3), respectively, with the following > values: > B = (/1,4/) ! Syntax (/.../) denotes an array constructor > C = (/2,1,1/) ! This constructor produces a many-one array section > > Array section A(3,B) consists of elements A(3,1) and A(3,4). Array > section A(C,1) consists of elements A(2,1), A(1,1), and A(1,1). Array > section A(B,C) consists of the following elements: > A(1,2) A(1,1) A(1,1) > A(4,2) A(4,1) A(4,1) > An array section with a vector subscript that has two or more > elements with the same value is called a many-one array section. For > example: > REAL A(3, 3), B(4) > INTEGER K(4) > ! Vector K has repeated values > K = (/3, 1, 1, 2/) > ! Sets all elements of A to 5.0 > A = 5.0 > B = A(3, K) > > The array section A(3,K) consists of the elements: > A(3, 3) A(3, 1) A(3, 1) A(3, 2) --
From: Tom Shelton on 12 Aug 2010 15:09 It happens that dpb formulated : > Tom Shelton wrote: > ... > >> It's funny, but I can't think of any statically compiled language that >> implements array slice functionality. It's seem to only be in the dynamic >> languages - Perl, Python, Ruby, etc..... > > Fortran for at least one...requires F90+, but that's now the norm and is 20+ > years old now... Ok... There's one. I'm not familar with fortran :) -- Tom Shelton
From: dpb on 12 Aug 2010 16:32 Tom Shelton wrote: > It happens that dpb formulated : >> Tom Shelton wrote: >> ... >> >>> It's funny, but I can't think of any statically compiled language >>> that implements array slice functionality. It's seem to only be in >>> the dynamic languages - Perl, Python, Ruby, etc..... >> >> Fortran for at least one...requires F90+, but that's now the norm and >> is 20+ years old now... > > Ok... There's one. I'm not familar with fortran :) BASIC w/ Do...EndDo instead of For...Next Syntax is very similar to BASIC; except for rather arcane features such as Fortran pointers (which aren't needed for anything ordinary as are for arrays, etc., in C or C-like languages but are handy for things like linked lists, etc.), syntax would mostly be readily understandable by a competent BASIC/VB user. _Extremely_ useful w/ VB as the backend for compute-intensive stuff since BASIC (and VB) inherited column-major array order from FORTRAN (now officially Fortran). The other way 'round sorta', of using VB as the frontend for its GUI features is the real reason I ever got into VB instead of Fortran entirely. --
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