Array Dimensions
In my code, i have two arrays. one for storing names and another to store a set of grades. The problem im having is defining the array dimensions.
The info is read in from a txt file so do i have to count the number of lines in the file in order to set the dimensions?
Use HashMap with [name(key) : grade(value)] pairs.
You don't need the total number of them beforehand.
Raw arrays should not be used as application's first
class data in a serious
Java project. Use java.util.Collection/Map family of
data structures instead.While I would tend to agree with the above suggestion, here's another idea for you:
if you use an ArrayList, you don't have to set the dimesion before hand. And if you're bent on using an array (as opposed to an ArrayList), there is a method of the List interface that returns an array (it's called toArray). So you could add everything to a LinkedList (faster than adding to an ArrayList), and get the contents back as an array.
But again, I recommend the HashMap approach.
- Adam
Similar Messages
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HELP: Run-time array dimension in LabVIEW formula node
I need to dimension an array at run time within a formula node as follows:
int32 i,N;
N = sizeOfDim(inputArray,0);
float64 outputArray[N];
for (i = 0; i outputArray[i] = myfunction(inputArray[i]);
However, LabVIEW complains "Formula Node: index list expected". On the
other hand, if I say
float64 outputArray[1000];
LabVIEW is perfectly happy. But that's not what I need to do! Is there
an alternative
way of accomplishing my goal?
BTW, I've tried calculating N outside the formula node and then
presenting it as
an input with the same results. I've got a bad feeling that run time
array dimensioning
just isn't allowed.
TIA,
HughCan't you just use the Initialize Array function outside the formula node and pass that instead?
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Array dimensions when converting from a cluster
Hello,
I am a beginner Labview programmer. Right now I am working on a VI
that converts a portion of cluster data to an array of tables. The
cluster is loop tunneled into a for loop then unbundled. I then build
it into a 2D array. When I hand the data back out of the for loop the
array dimensions are the same size. i.e. If the 2D arrays were 2x7 and
2x6 going in then going out I have both as 2x7's. This happens right
at the exiting loop tunnel (I suppose when it initializes the 3D
array). This places zeros in the last row of my 2x6 array. Can anyone
suggest a fix. Thanks a bunch.
Peter.Hi, Peter:
I think you want to have an array of different row sizes. I think it's impossible in LabView. At least using only arrays and without clusters.
And as all rows have the same number of elements, undefined elements get default value. In case of numerics, zeros.
You could create an array of cluster elements, and each element be an array 2D. Then each element can be an array of different sizes.
But that's just what you had at start.
Aitortxo.
Aitortxo. -
On the front panel is an array of dbl. I want to only allow the user to select four (0-3) using the index display. How can I limit the index display?
Solved!
Go to Solution.
Attachments:
Array dimensions.vi 6 KBYou can hide the index display, then make a seperate control where you can set entry limits. Use a value change event on it to set the "index values" property to scroll the array. Make the upper limit of the control dependent on the size of the array and the number of elements visible.
For example, if the array is size=4 and the display is size=3, only allow 0..1 on the control using data entry limits.
You could even wrap the entire thing into an xcontrol. The advantage of an xcontrol is the fact that is also work in edit mode.
Message Edited by altenbach on 02-01-2010 09:35 AM
LabVIEW Champion . Do more with less code and in less time . -
Exchange 2013 Public Folders Array Dimensions Have Exceeded Supported Range
Hello,
I have another odd issue for public folders on Exchange 2013. I am working with an environment with a bit over 3000 Public Folders and we are having some issues where some users are not able to access the public folder. When I try to change the permissions
to those folders I get the error of:
"Array Dimensions Have Exceeded Supported Range"
The environment is a 2 Node DAG with all components installed on each server. The latest Roll Up has been in stalled on both servers as well.
Thanks in Advance
JoeUpdate the thread if you find the resolution...
Cheers,
Gulab Prasad
Technology Consultant
Blog:
http://www.exchangeranger.com Twitter:
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Note: Posts are provided “AS IS” without warranty of any kind, either expressed or implied, including but not limited to the implied warranties of merchantability and/or fitness for a particular purpose. -
Hi,
For the following declaration I am getting "Array Dimension Too Big" error with Forte C Compiler on Solairs 8.
double try[23200][23000];
What is the mx dimension possible? and Where do I find such info on boundary conditions??
Regards,
GurudattaHi There,
The legal limit of the array is whatever the hardwareand swap space will support.
You are asking for 8*23000*20000 bytes /1024/1024 = 3509.52 megabytes = 3.43 gigabytes.
You are declaring this much allocation locally via
automatic array in your example. You'll have to define a stack this size (hardly practical).
If you ask for this much memory with malloc() which is a much better idea, you'll still need to have enough swap.
You can also do mmap(...,MAP_NORESERVE,...) in which case you may not even need the swap to support it.
It all depends on what you are doing and why.
.....jagruti
Developers Technical Support
Sun Microsystems, http://www.sun.com/developers/support -
Simple Array Dimensioning question
Hey all,
What is the easiest way to dynamically set the array dimension of an array? I have a method that returns an object array of type Project. The array size of the returned object varries depending on what parameters are passed. I do not know how to declare the object that calls the method. Can you help me? Thanks.
DetailedProject[] test = new DetailedProject[5];
test = myBudgetDAO.getProjects("2006","O&M","25","109","98");Would I still be able to call the same method with different parameters? Yes. All you say is that the method is returning an array.
The size of the array matters not to your main program, just that the method returns an array of the appropriate objects.
Something in your getProjects method you must be declaring/creating an array. Look at that code.
The getProjects method must know how many to create if it is returning the correctly sized array.
An alternative is instead of using an array, to use a List (eg ArrayList) which dynamically resizes itself, and you don't need to set inital capacity. -
Max array dimension for Speedy 33?
Hi all,
Does any body know what the max array dimension for Speedy 33? I am able to create 1-row arrays, but not arrays more than 1 rows..
Thanks so much in advance!
~CassiopeaThere is a really good knowledge base article on our website that discusses in detail how arrays are handled using LabVIEW DSP and how you should use them. It has exactly what you're looking for.
How Can I Be Successful With Arrays In the LabVIEW DSP Module?
Good luck with your application!
Nick R
NI -
Timed loop with array dimension control
Hello,
I have imported an excel to an array and im trying to use a timed loop to run the values of the array on a timed interval. One of my problems is that the array is 2D and i cant use its length to stop the loop. I want to use witch value of the array in the loop in each iteration of the loop and i want the loop o stop when the counter equals the length of the array. Can someone help me plz here is the labview.It is really unclear what your question is. Could you clarify?
If you are struggling with why you have a broken wire it is because you are sending an array to the stop of the loop. When you use the array size function on a 2D array it returns a 1D array with the size of each dimension. When you then use the greater than function it returns a 1D array of Booleans. It compares each element of the array size to the current count of the iteration terminal.
To use this to stop your loop you need to reduce it to a single element some way before you send it to the stop control of the loop. You could apply an "and" or "or" function to the out put of the greater than or pull out a single index out of the single greater than array.
In the image logical AND, logical OR, or element could be used to stop the loop. You just need to choose one that gives you the behavior you need.
Lukin
Certified LabVIEW Developer -
I am passing a two dimension array to the function in which second dimension is always same(means no of column) that is four.
First dimension is variable that is four or five or what so ever.(means number of rows are variable).
In the function I have to loop through the number of rows.
So is there any array function to find the length of first dimension.
e.g
some time the array is arr[2][4]
some time it is arr[8][4]
I want to get array first dimension that is here 2 or 8.Length shouldn't (can't) be capitalized if you want it to work.
What are you doing with arrcnt? Java is not C. You can't address 2-D arrays as 1-D arrays. You need an inner loop instead of your if (k%4==0).
for(int k=0;k<arr.length;k++)
for(int col=0;col<arr[k].length;col++) // could use 4 instead of arr[k].length
//do whatever with:
arr[k][col] = ...;
} -
Arrays dimension changed by "for loop"
When using a two(multi)-dimension array as input to a "for loop", the connection
changes inside the loop to a 1D array automatically. Why?!?
I want to perform the same procedure on each subarray of the basic two-dimension
array, by specifing an index. The second dimension I disable indexing. The
index itself can be the for loop index. The problem is the change in connection
between out and in of the for loop.The question is that you have indexing enabled in the for
loop entry, and the for loop will convert your 2D array in
the necessary number of 1D arrays to be completed in the
for loop. This is good when you don't know how long the
array is going to be, but if you don't like it, you can
right click on the input tunnel and disable indexing.
Hope this helps.
* Sent from AltaVista http://www.altavista.com Where you can also find related Web Pages, Images, Audios, Videos, News, and Shopping. Smart is Beautiful -
Maximum number of dimensions for an array
What is the maximum number of dimensions an array can accept:
a. 266
b. 255
c. 256
d. 250
which option is correct and why?sabre150 wrote:
I don't know and I most definitely don't care since anything more than 2 is, in my opinion, just silly.It's also quite untractable from a memory standpoint. Say you have an 10 by 10 by 10 array. That's 10^3 elements. Now say you have 250 dimensions, that's 10^250 elements which is a huge number in the order of the number of atoms in the universe or so.
Say you instead have just 1 element in each dimension. Then you got a total of 1^250 elements, which is 1 element. That's okay but you don't need the array because 1 element is a variable. This means an array has at least 2 elements in each dimension. That's 2^250 elements which is like 10^75 which is also a huge number. You wouldn't get that kind of memory even if you added up all computers that ever existed.
So array dimensions in the order of 250 aren't just silly, there isn't enougth memory for them. -
hi,JDC people.
i want to use a 2-dimension array, the length of the first dimension is know, the length of the second dimension varies. how could i define and add elements to the array? shall i use ArrayList?
can anyone give some hint or simple example? thanks.In Java, you don't (strictly speaking) have a two-dimensional array, you have an array of arrays.
If you know the length of the first array (dimension), you can declare it thusly:Object[][] objectsArray = new Object[2][]; // You've declared and initialised one 'dimension';You can then declare each of the second arrays (dimensions) in turn:objectsArray[0] = new Object[5];
objectsArray[1] = new Object[936];
// etc.You then refer to each Object in the array(s), like this:Object something = objectsArray[0][3]; // Fourth object in first array
Object somethingElse = objectsArray[1][935]; // 936th object in second arrayHope this is helpful...
Chris. -
Iteration Speed issue when Indexing 3D array wried to a while-loop
Brief Description of my Program:
I am working on the real-time signal generation by using LabView and DAQmx (PCI-6110 card). My vi reads the big data file (typically 8MB txt file containing about 400,000 samples (complex double precision). Then, the signal is pre-processed and I end up with a huge 3D array to feed while-loop (typically 3D array dimension is N x 7 x M where N & M >> 7). Inside the loop, that 3D array is indexed and processed before the results are written to the DAQmx outputs. I have a speed issue when indexing the large 3D array (i.e, 3D array having a large sub-array size). My while-loop could not run fast enough to top-up the DAQmx AO buffer (at the output rate of 96kHz). It could run faster only if I use smaller 3D array (i.e, smaller-sized sub-arrays). I do not quite understand why the size of 3D sub-array affects the rate of looping although I am indexing same sub-array size at each iteration. I really appreciate your comments, advices and helps.
I include my 3D array format as a picture below.
Question on LabView:
How does indexing an 3D array which wires to the while-loop affect the speed of the loop iteration? I found that large dimension of sub-arrays in the 3D array slows down the iteration speed by comparing to indexing the same size of sub-array from smaller-sized sub-arrays of the 3D array to perform signal processing inside the while-loop. Why? Is there any other way of designing LabView Program to improve speed of iteration?
attachment:Thank you all for your prompt replies and your interests. I am sorry about my attachment. But, I have now attached a jpg format image file as you suggested.
I had read the few papers on large data handling such as "LabVIEW Performance and Memory Management". Thus, I had already tried to avoid making unnecessary copies of data and growing arrays in my while-loop. I am not an expert on LabView, so I am not sure if the issues I have are just LabView fundamental limitations or there are any other ways to improve the iteration speed without reducing the input file size and DAQ output rate.
As you request, I also attach my top-level vi showing essential sections such as while-loop and its indexing. The attached file is as an image jpg format because the actual vi including Sub-VIs are as big as 3MB in total. I hope my attachment would be useful for anyone who would like to reply my question. If anyone would like to see my whole vi & llb files, I would be interesting to send it to you by an e-mail privately and thus please provide your e-mail address.
The dimension of my 3D array is N x 7 x M (Page x Row x Column), where N represents number of pages in 3D array, and M represents the size of 1D array. The file I am currently using forms 3D array of N = 28, & M = 10,731. Refering to the top-level vi picture I attached, my while-loop indexes each page per iteration and wrap-around. The sub-VI called "channel" inside the while-loop will further index its input (2D array) into seven of 1D arrays for other signal processsing. The output from that "channel" sub-VI is the superposition of those seven arrays. I hope my explaination is clear.
Attachement: 3Darray.jpg and MyVi.jpg
Kind Regards,
Shein
Attachments:
3Darray.jpg 30 KB
MyVI.jpg 87 KB -
Trouble with primitive arrays and casting, lesson 521
hi everyone!
there is a problem i discovered right now - after years with java where was no necessity to do this.....
and i'm shure this must have been the topic already, but i couldn't find any helpful resource :-/
right here we go:
1. an array is a (special) kind of object.
2. there are "primitive" arrays and such containing references to objects. of course - and i imagine why - they are treated differently by the VM.
3. then both are - somehow - subclasses of Object. whereas primitive types are not really, primitive-arrays are. this is hidden to the programmer....
4. any array can be "pointed" at via local Object variable, like this:
Object xyz = new int[6];
5. arrays of Objects (with different dimensions) can be casted, like this:
Object pointer = null;
Object[] o = new SomeClass[42] ;
Object[][] oo = new OtherClass[23] [2] ;
Object[][][] ooo = new OtherClass[23] [2] [9] ;
o = oo = ooo; // this is save to do,
//because "n-dimensional" object-arrays
// are just arrays of other arrays, down to simple array
pointer = o; // ok, we are referencing o via Object "pointer"6. but, you cannot do this with primitive types:
int[] i1 = new int [99] ;
int[][] i2 = new int [1] [3] ;
i1 = i2 // terror: impossible. this is awful, if you ask me.
// ok, one could talk about "special cases" and
// "the way the VM works", but this is not of interest to me as
// a programmer. i'm not happy with that array-mess!
pointer = i2; // now this is completely legal. i2, i1 etc is an object!7. after the preparation, let's get into my main trouble (you have the answer, i know!) :
suppose i have a class, with methods that should process ANY kind of object given. and - i don't know which. i only get it at runtime from an unknown source.
let's say: public void BlackBox( Object x );
inside, i know that there might be regular objects or arrays, and for this case i have some special hidden method, just for arrays... now try to find it out:
public void BlackBox( Object x )
if ( x == null)
return;
Class c = x.getClass();
if ( c.isArray() )
// call the array method if it's an array.........
BlackBoxes( (Object [] ) x ); // wait: this is a cast! and it WILL throw an exception, eventually!
return;
else
DoSpecialStuffWith( x );
}ok ? now, to process any kind of array, the special method you cannot reach from outside:
private void BlackBoxes( Object[] xs )
if ( xs != null )
for ( Object x : xs )
BlackBox( x );
// this will end up in some kind of recursion with more than one array-dimension, or when an Object[] has any other array as element!this approach is perfectly save when processing any (real) Object, array or "multi-dimensional" arrays of Objects.
but, you cannot use this with primitive type arrays.
using generics wouldn't help, because internally it is all downcasted to Object.
BlackBox( new Integer(3) ) ---- does work, using a wrapper class
BlackBox( new Integer[3] ) ----- yep!
BlackBox( 3 ) ---- even this!
BlackBox( new int[42] ) ---- bang! ClassCastException, Object[] != int[]
i'm stuck. i see no way to do this smoothly. i could write thousands of methods for each primitive array - BlackBox( int[] is ) etc. - but this wouldn't help. because i can't cast an int[][] to int[], i would also have to write countless methods for each dimension. and guess, how much there are?
suppose, i ultimately wrote thousands of possible primitive-type methods. it would be easy to undergo any of it, writing this:
BlackBox( (Object) new int[9] [9] );
the method-signature would again only fit to my first method, so the whole work is useless. i CAN cast an int[] to Object, but there seems no convenient way to get the real array out of Object - in a generic way.
i wonder, how do you write a serialisation-engine? and NO, i can't rely on "right usage" of my classes, i must assume the worst case...
any help appreciated!thanks, brigand!
your code looks weird to me g and i think there's at least one false assumption: .length of a multidimensional array returns only the number of "top-level" subarrays. that means, every length of every subarray may vary. ;)
well i guess i figured it out, in some way:
an int is no Object;
int[ ] is an Object
the ComponentType of int [ ] is int
so, the ComponentType of an Object int[ ] is no Object, thus it cannot be casted to Object.
but the ComponentType of int [ ] [ ] IS Object, because it is int [ ] !
so every method which expects Object[], will work fine with int[ ] [ ] !!
now, you only need special treatment for 1-dimensional primitive arrays:
i wrote some code, which prints me everything of everything:
//this method generates tabs for indentation
static String Pre( int depth)
StringBuilder pre = new StringBuilder();
for ( int i = 0; i < depth; i++)
pre.append( "\t" );
return pre.toString();
//top-level acces for any Object
static void Print( Object t)
Print ( t, 0);
//the same, but with indentation depth
static void Print( Object t, int depth)
if ( t != null )
//be shure it is treated exactly as the class it represents, not any downcast
t = t.getClass().cast( t );
if ( t.getClass().isArray() )
//special treatment for int[]
if ( t instanceof int[])
Print( (int[]) t, depth);
// everything else can be Object[] !
else
Print( (Object[]) t, depth );
return;
else
System.out.println( Pre(depth) + " [ single object:] " + t.toString() );
else
System.out.println( Pre(depth) + "[null!]");
// now top-level print for any array of Objects
static void Print( Object [] o)
Print( o, 0 );
// the same with indentation
static void Print( Object [] o, int depth)
System.out.println( Pre(depth) + "array object " + o.toString() );
for ( Object so : o )
Print( so, depth + 1 );
//the last 2 methods are only for int[] !
static void Print( int[] is)
Print( is, 0 );
static void Print( int[] is, int depth)
System.out.println( Pre(depth) + "primitive array object " + is.toString() );
// use the same one-Object method as every other Object!
for ( int i : is)
Print ( i, depth + 1 );
System.out.println( "-----------------------------" );
}now, calling it with
Print ( (int) 4 );
Print ( new int[] {1,2,3} );
Print( new int[][] {{1,2,3}, {4,5,6}} );
Print( new int[][][] {{{1,2,3}, {4,5,6}} , {{7,8,9}, {10,11,12}}, {{13,14,15}, {16,17,18}} } );
Print( (Object) (new int[][][][] {{{{99}}}} ) );
produces this fine array-tree:
[ single object:] 4
primitive array object [I@9cab16
[ single object:] 1
[ single object:] 2
[ single object:] 3
array object [[I@1a46e30
primitive array object [I@3e25a5
[ single object:] 1
[ single object:] 2
[ single object:] 3
primitive array object [I@19821f
[ single object:] 4
[ single object:] 5
[ single object:] 6
array object [[[I@addbf1
array object [[I@42e816
primitive array object [I@9304b1
[ single object:] 1
[ single object:] 2
[ single object:] 3
primitive array object [I@190d11
[ single object:] 4
[ single object:] 5
[ single object:] 6
array object [[I@a90653
primitive array object [I@de6ced
[ single object:] 7
[ single object:] 8
[ single object:] 9
primitive array object [I@c17164
[ single object:] 10
[ single object:] 11
[ single object:] 12
array object [[I@1fb8ee3
primitive array object [I@61de33
[ single object:] 13
[ single object:] 14
[ single object:] 15
primitive array object [I@14318bb
[ single object:] 16
[ single object:] 17
[ single object:] 18
array object [[[[I@ca0b6
array object [[[I@10b30a7
array object [[I@1a758cb
primitive array object [I@1b67f74
[ single object:] 99
-----------------------------and i'll have to write 8 methods or so for every primitive[ ] type !
sounds like a manageable effort... ;-)
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