Deleting an array

I'm using 3 arrays in a program but i repeat the program once becuase i have to do 2 different websites so i don't want to have to write a whole nother set of code is there anyway i can just delete the whole array and use it again ?

Simply reinstantiate it?existingStringArray =
new String[];
yeah, just reuse the variable name

Similar Messages

Memory/Speed of Split 1D array vs Delete from array

Just wondering how Split 1D array works - does it create two new arrays in a new section of memory or does it just split the existing array in two, reusing the memory in place. (assuming that the original array is not needed elsewhere). If the latter is the case then presumably it is more efficient to use split array than delete from array if I want to remove element(s) from the beginning or end of the array. Is there a speed advantage as well?
If I use split array but don't then use one of the output arrays is that memory deallocated or does the array remain in memory?
Thanks
Dave

Ok please ignore the results I posted earlier, they are rubbish - not least because I got the column headings mixed up but also because my code was full of bugs
So, here is a revised table, and the code - which hopefully only contains a few bugs... I'm not clued into benchmarking yet so please feel free to rip the code apart.
I still get different results depending on where in the array I split it, most noticeably with subset and reshape. There is no effect with split. I'm guessing this is to do with the memory allocation. (I have not preallocated memory in my code, but I did wire the output arrays to Index Array)
Message Edited by DavidU on 08-12-2008 04:49 PM
Attachments:
Benchmarks 2.png ‏13 KB
split array test.vi ‏25 KB

Deletion of arrays during specific time intervals...how to get it working?

i am trying to calculate the average peak values in a systolic pressure waveform during a specific time interval. for example, every 5 seconds, i want to average out all the peak values in that interval and after calculating the average, i want to delete the array of peak values. however, what i am finding is that the array is always 0 if i use the delete array in my vi. therefore, the average is always NaN, because the array is empty and there is a divide by 0 error....
what should i do? i have been stuck on it for a long time now, thankyou very much"
Attachments:
help.vi ‏57 KB

It is very difficult to make sense of your diagram, because all the control references are missing, so it is not possible to tell the various data sources apart.
Where is the data coming from? How do you prevent race conditions between the acquisition and analysis parts?
Overall, the diagram is overly complicated and very hard to read. For example clearing the array does not require reading the old array, measuring it's length, followed by "delete from array", followed by writing back to the array. Why don't you just wire an empty array to it? Same result! :-)
You go to tremedous lenght calculating a simple array average, using numerous property reads and indexing arrays inside FOR loops. There is "mean.vi" that does it in one step. (If you only
have base LabVIEW, it might not be available (?), so use "Sum" and divide by n. No loop needed). To find the largest element in an array, use "Array Max & Min" from the array palette, again in one simple step.
I would highly recommend going over some LabVIEW tutorials or look at some of the shipped examples. Make yourself familiar with basic programming concepts such as auto-indexing at loop boundaries. An "index array" wired to the loop counter is never needed.
I suspect that your problem is due to a race condition between acquisition and analysis code, but there is no way to tell unless you include all control references and also the companion VI that gets the raw data from the instrument.
LabVIEW Champion . Do more with less code and in less time .

Can somebody help me with deleting an array

Can somebody help with deleting an array

Hi Sansom,
If you want to delete an array rather than format a volume you need RAID Admin which can be downloaded here.
http://support.apple.com/kb/DL288 if you just want to delete the contents of the volume you can do this with Disk Utility.
You'll also need to make sure the Xserve RAID is plugged in with one Ethernet connection and is on the same network as the machine you run RAID admin on.
Then run RAID Admin and enter the password. In General the password is "private" to make changes or "public" to view the configuration.
Hope that helps
Beatle

Deleting dynamic arrays

My main concern is worrying about having a memory leak due to a program crashing before it has the chance to reach the line of code in which technically releases its memory. What I do not understand is, if the program does crashes before it can release the memory of any dynamic arrays, wouldn't the memory leak still exist the next time you run the program and causing the leak to get worse each time?
for example, if I had something like this...
int main()
int *a = new int[10];
bool game = true;
// then for some reason the program crashes somewhere along these lines...
while(game) {
do some code in which some reason cause the program to crash
delete [] a;
return 0;
here in the example, if the program had crashed inside the while loop, wouldn't I have a memory leak which exist forever?

BnTheMan wrote:
The first instance is I wanted to know after reading some topics on the internet, I have heard that is is not a good Idea to set a pointer to know inside of a constructer class like this...
should you do this, or does it depend on the compiler that you use, and what about if you are using XCode?
Did you mean to type "not a good Idea to set a pointer to NULL"? That is what you code seems to say.
They key part is memory management. People have been screwing that up for decades. You should initialize pointers to NULL or 0 (same thing) before using them. Then, when you are done with them, if they aren't NULL, you must release them. Even if you haven't allocated a pointer, you can always release it if it is NULL using free(), delete, or release - depending on what language you are using.
If you allocate a pointer, then release its memory, you should re-set it back to NULL immediately if there is any chance that some other bit of code could try to release the memory. If you try to free a pointer twice, your app will crash.
All this is true in any environment that doesn't have garbage collection. Don't think that garbage collection is the panacea it is made out to be. It is better to be able to manage your own memory when you need to. Plus, there are more system resources than just memory.
2. The next thing I noticed was that it did not have any memory releasing code for when there is a problem with reading the file, such as if the file could not be opened. So I am wondering if something was to happen when opening the second MD2 file, in that it could not open the file because it was currupted, and I did something like this...
MD2_Object::loadObject() {
ifstream inFile;
char buffer[64];
inFile.open(myFile, istream::binary);
if(!inFile) {
... the code I need to my question
How can I tell the program that there was an error and that it needs to release the memory from the first dynamic array variable?
(I added some { code } statements to format your code nicely. Reply to this post to see how I did it.)
That is a good question, with several caveats. In your example, you are actually using static variables, not dynamic. All of your data is allocated on the stack. You didn't use any sort of malloc(), new, alloc, etc. Therefore, memory management is easy. When the current scope ends (usually the code between braces) anything allocated on the stack automatically goes away cleanly. Plus, since the stack is much more low level than dynamic memory, you can do stack allocations much more quickly.
But, had used dynamic allocation, this would be an issue. It is a significant problem that is rarely handled correctly. If there is an error, you need to release any resources (such as memory) that you have allocated. There are a number of ways to handle this, depending on your language and how you want to do it.
The first solution is to exploit the fact that, in C++, you can declare your variables anywhere you want. They don't have to be at the beginning of the scope. The best thing to do is don't allocate resources unless you know you can use them. If you fail halfway through, you would have to release all resources that you had allocated up to that point.
Some other ideas are to use exceptions and wrap allocations in classes such as auto_ptr. Then, when you encounter an error, you throw and exception and you use the stack scoping rules, though static wrapper variables, to release dynamic data underneath.
Yeah, it gets complicated. Maybe most more code that precisely shows what you are concerned with. Wrap your code between two lines of
{ code }
{ code }
without the spaces and it will print out nicely. So far, it looks like you are doing everything correctly. Sometimes, instead of asking how to do something, you'll get better responses by just posting how you do it and, if there are any problems, people will pick it apart Harsh, but effective.

How to delete rows from 2D array in this case...

Hello. I'm just begging adventure with labview so please for patient. I created a program whitch suppose work in following way:
2D Input array is array created by FOLDER BROWSING subVI. It works in this way,that browse folder and looking for txt files whose contanins measurment data. In my case subVI founds 4 files,and from theirs headers read information about what kind of data are in file also their's path. In this way is created 2D Input Array. subVI named PLOTS FROM PATHS ARRAY make picture with polar/XY plot. It's create only those plots and legends on one picture as many files(their paths) is setted to the program by output array. I made this subVI in that way and I would not like to change it.
My problem is that in even loop (witch check for any change by user) program suppose to relay anly those rows(files) for which checkbox are marked, e.g. marking anly 1 and 4 box, program should chose from input array row 1 and 4 only and pass them to output array,then PLOTS FROM PATHS ARRAY subVI makes a picture only with 1 and 4 plot and legend only for plot 1 and 4. The best solution would be some relay witch is avtivated by logical signal. It lost to me ideas how to solve it, I'm just in blaind corner...
I tried to use delete from array but I don't know how to do use it properly in this program,becease it can be only before or afeter for loop. Below is scan of front panel and also main problem. Please set me up somehow to solve this problem.
Regards
Solved!
Go to Solution.
Attachments:
plots selector.vi ‏17 KB
problem.PNG ‏18 KB

I have attached a vi. Is this the one that you need?
Anand kumar SP
Senior Project Engineer
Soliton Technologies Pvt Ltd
Attachments:
plot selector modified.vi ‏14 KB

How can I do to delete some lines of a 2D array when I push a button ?

With Labview 5.1 : I have a 2D array and I want to delete a line ( I think to delete its first one or its last one could be easier) when I push a control button. How can I do ?
Regards.
Cyril.

I only have LV 6.1, take a look the pic and hopefully that will help. You need to use delete from array and then select which row or column you want to delete. then put it inside the case structure.
Best Regards,
Saw
Attachments:
test.bmp ‏81 KB

Completely messed up Raid-Array and Partition! How to delete and create new Raid-Array?

Hello,
I am using Ideapad U310 and tried to clean install Windows 8 and use my SSD as CACHE and Hibernate-Partition.
So, I was able to get to the Intel CTRL+I-RAID Config Menu and there I was able to create and delete my RAIDS.
Unfortunately I did not setup the Partition Size correctly, thus I only have a 50 GB Partition combined with my SSD and my HDD. This is what it looks like in the Intel Storage Manager:
As you can see both, my SSD and HDD appears, but only have small partitions on the right. And Windows 8 only recognizes this small partitions, as you can see here:
And now I am NOT able to get to the Intel RAID CTRL+I-menu before Windows starts, where I could delete this array.
My Partitions are "empty", so I dont care if anything is delete. I just want to use raid with FULL CAPACITY of my harddrives. But how can I delete the RAID Arrays and reconfigure them correctly?
When I change in the BIOS from RAID to AHCI I am able to install Windows 8 again with the whol CAPACITY of my SSD and HDD. But then I will not be able to use the RAID via Intel Storage Manager...
Hopefully someone could help me.
Thank you in advance.

Hi
Please see this thread
http://forums.lenovo.com/t5/IdeaPad-Y-U-V-Z-and-P-series/The-Guide-on-How-To-Reformat-Repartition-AN...
Hope this helps
Ishaan Ideapad Y560(i3 330m), Hp Elitebook 8460p!(i5-2520M) Hp Pavilion n208tx(i5-4200u)
If you think a post helped you, then you can give Kudos to the post by pressing the Star on the left of the post. If you think a post solved your problem, then mark it as a solution so that others having the same problem can refer to it.

Delete rows from array

Hello,
I am attempting to delete the rows that contain a multiple of the x-data from the original array and have the output array show the original array minus the delete harmonics array.
Original array:
100 3
200 18
300 13
400 8
500 0
600 0
700 0
delete rows that contain multiples of 300. Output array will be
100 3
200 18
400 8
500 0
700 0
Any help will be sincerely appreciated.
Thanks,
hiNi.
Solved!
Go to Solution.
Attachments:
delete rows.vi ‏14 KB

Hello,
I wanted to further expand on this program as follows:
I wanted to delete the rows that are a multiples of the fundamental entry. However, the multiples of the fundamental are not always an exact multiple, they can differ by up to 3M. So, from the origial array,:
130.4M -65.386
149.4M 9.6346
172.2M -64.981
301.4M -17.273
426.8M -68.169
449.6M -820.72m
472.4M -66.132...
with the multiples of 149.4M deleted, the output array should be:
130.4M -65.386
172.2M-64.981
426.8M -98.169
472.4M -66.132...
Any help will be greatly appreciated!
Thanks,
hiNi.
Attachments:
delete rows 2.vi ‏13 KB

I want to insert 2d array (XY position)to XY graph and can delete the data from the array too.

Firstly, I receive the data of X and Y position one by one seperately and then I add this two value (numeric double) to array two column (XY). After I press ok button the new data for X and Y will come and be added to the last row of my data. Then I use this data to plot in XY graph. All of this I did it already, but I want more additional function.
My additional function is I want to add or delete a pair of data XY from the array at the row that I defined. This one I can not do it.....

You use the Insert Into Array and Delete From Array functions on the Array palette. Here's a simple example in 6.0 that shows how they're used.
Attachments:
Insert_and_Remove_Row.vi ‏50 KB

Clearing an array without deleting it

What would be the fastest way of clearing an array without
deleting it? Could you set all values to null or undefined and it
would work? For example, say I have an array of 4 numbers: 3, 4, 5,
6. Now, for some reason I want to clear all the values and set only
one value, so now I have an array of 1 number with a length of only
1: 7. How can I do this without deleting the array? Remeber, I only
want this array to have a length of one, not 4.

u could try this one may be it should work for ur
requirements.
var myArray:Array = new Array(1, 3, 4, 5)
myArray.length = 1;
trace(myArray)

Delete array icon won't expand

Hi,
Does anyone have problem with "delete array" icon that won't expand to accept more indexes? From the Context help, it shows the delete array icon as expandable, but it won't work.
thanks,
atd
Solved!
Go to Solution.

No, the node is not expandable. I guess the image in the context help indicates how the node adapts to higher dimension input arrays.
Having the node expandable would be very dangerous because the indices assigned to elements of course change with every deletion. If you need to delete many sections, htere are much better ways to do this. "Delete from array" should typically not be used repetitively (e.g. in a tight loop).
For some better ideas, have a look at this post. As you can see here, doing it efficiently can be orders of magnitude faster. Is your array 1D, 2D or higher?
LabVIEW Champion . Do more with less code and in less time .

Keyboard Delete button to delete row in array

Is there a way to use the delete key on the keyboard to delete a row from an array?

Hi Liz,
If you are Using LV 6.1, this is easily done. There are three steps to the Process.
1. Trap the Event when the Delete Key is Pressed. With LV 6.1 Event Structure can do this and give you which Key is Pressed Using VKey Node.
2. There must be Some way that you can identify which row must be deleted. It could be a Simple Slider or Program output.
3. The Physical deletion from the Array. With 6.1 you get a function "Delete from Array" and you specify either Column no or Row No to Delete.
I have Attached a Sample VI for you to see in LV 6.1
If you Do not Have LV 6.1 then Action 1 to Trap Delete Key Stroke is not In built LV function. You may Want to get "Danny Lauers ToolBOx" I think it is available at www.openG.org
There is a Functi
on in there"Get Keys" which will tell which Key is Pressed.
Then you will have to Build Funtionality to Manipulate Array to Delete the row.
Good Luck!!
Mache
Good Luck!
Mache
Attachments:
Delete_Row_from_Arry.vi ‏30 KB

Large Arrays and Memory

I'm supposed to be working on code for a lab, and they have reported possible problems with labVIEW eating through memory on long experiments. Someone before me tried to fix the problem but I am unsure if it is actually helping. (I'm more familiar with languages like C++, and have not used labVIEW prior to this summer).
Where I believe the problem lies is with the array (within a loop). Depending on the experiment the arrays will be of different sizes so how they handle the array is:
-> It is an array of a cluster of 2 elements
-> The array is wired to a shift register.
-> The shift register is initialized prior to the loop opening by wiring the shift register to a cluster of 2 "0's".
->Each loop cycle they add new data (a new cluster) to the array using "Build Array"
There are multiple of these arrays all being plotted so they use "Build Cluster Array" and then wire it to the corresponding Plot (an XY Graph). They use this after "Build Array".
This used to be it, so the arrays would grow large and crash the program. Someone before me added an option to clear the arrays, but I am unsure if the way she designed it actually releases the memory since they are still reporting some problems. The user enters a number in a control "Clear After:". On every iteration that is a multiple of that number, the program passes the shift register an array with one element. The array that is passed set up the same as the array passed for the initialization process.
My concern is that the code never specifically says delete the array or release the memory. It feels very similar to the situation in C++ when the programmer dynamically creates an array (using new) but never deallocates the array (using delete), instead they just change where the pointer is pointing. There the memory would still be tied up and unusable.
So I guess my question is, looking at the process above do I need use "Delete from Array" to release the memory and allow the program to run faster on longer experiments with large datasets or does labVIEW automatically deallocate that memory and therefore I should I be looking elsewhere in my program for processes that would slow down everything on longer experiments?
Thanks,
Val
Solved!
Go to Solution.

I have attached a photo of the portion of code that I was referring to. It shows 2 photos so you can see all possibilities in the 2 case statements.
The first picture is when the cycle is adding new data points, and does not clear the array.
The second picture shows the program passing through the array (which it does every second cycle) and then "clearing" the array. (Which as I state above, I didn't know if that was correct).
(None of this is actually my code, I was hired on to upgrade them from labVIEW 5.1 to labVIEW 2009. They just asked me to look at this. It seems to work fine on smaller length experiments on the order of a couple of hours). If you need anything else from me, don't hesitate to ask.
Thanks,
Val
Attachments:
loop.docx ‏105 KB

What is the best way of dealing with an "implicit coercion" of an array to a sprite?

Hello everyone!
     With continued help from this forum I am getting closer to having a working program. I look forward to being able to help others like myself once I finish learning the AS3 ropes.
     I will briefly explain what I am trying to achieve and then follow it up with my question.
Background
     I have created a 12 x 9 random number grid that populates each cell with a corresponding image based on each cell's numeric value. I have also created a shuffle button that randomizes the numbers in the grid. The problem I am running into is getting my button-click event to clear the current images off the grid in order to assign new ones (i.e. deleting the display stack objects in order to place news ones in the same locations).
Question
     My question is this: what is the best way to handle an implicit coercion from an array to a sprite? I have pasted my entire code below so that you can see how the functions are supposed to work together. My trouble apparently lies with not being able to use an array value with a sprite (the sprite represents the actual arrangement of the grid on the display stack while the array starts out as a number than gets assigned an image which should be passed to the sprite).
============================================================================
package
import flash.display.MovieClip;
import flash.display.DisplayObject;
import flash.events.MouseEvent;
import flash.display.Sprite;
import flash.text.TextField;
import flash.text.TextFormat;
import flash.utils.getDefinitionByName;
public class Blanko extends MovieClip
      // Holds 12*9 grid of cells.
      var grid:Sprite;
      // Holds the shuffle button.
      var shuffleButton:Sprite;
      // Equals 12 columns, 9 rows.
      var cols:int = 12;
      var rows:int = 9;
      // Equals number of cells in grid (108).
      var cells:int = cols * rows;
      // Sets cell width and height to 40 pixels.
      var cellW:int = 40;
      var cellH:int = 40;
      // Holds 108 cell images.
      var imageArray:Array = [];
      // Holds 108 numerical values for the cells in the grid.
      var cellNumbers:Array = [];
      // Constructor calls "generateGrid" and "makeShuffleButton" functions.
      public function Blanko()
           generateGrid();
           makeShuffleButton();
// Creates and displays the 12*9 grid.
private function generateGrid():void
       grid = new Sprite;
       var i:int = 0;
       for (i = 0; i < cells; i++)
            cellNumbers.push(i % 9 + 1);
       trace("Before shuffle: ", cellNumbers);
       shuffleCells(cellNumbers);
       trace("After shuffle: ", cellNumbers);
       var _cell:Sprite;
       for (i = 0; i < cells; i++)
            // This next line is where the implicit coercion occurs. "_cell" is a sprite that tries
               to temporarily equal an array value.
            _cell = drawCells(cellNumbers[i]);
            _cell.x = (i % cols) * cellW;
            _cell.y = (i / cols) * cellH;
            grid.addChild(_cell);
// Creates a "shuffle" button and adds an on-click mouse event.
private function makeShuffleButton():void
       var _label:TextField = new TextField();
       _label.autoSize = "center";
       TextField(_label).multiline = TextField(_label).wordWrap = false;
       TextField(_label).defaultTextFormat = new TextFormat("Arial", 11, 0xFFFFFF, "bold");
       _label.text = "SHUFFLE";
       _label.x = 4;
       _label.y = 2;
       shuffleButton = new Sprite();
       shuffleButton.graphics.beginFill(0x484848);
       shuffleButton.graphics.drawRoundRect(0, 0, _label.width + _label.x * 2, _label.height +
                                            _label.y * 2, 10);
       shuffleButton.addChild(_label);
       shuffleButton.buttonMode = shuffleButton.useHandCursor = true;
       shuffleButton.mouseChildren = false;
       shuffleButton.x = grid.x + 30 + grid.width - shuffleButton.width;
       shuffleButton.y = grid.y + grid.height + 10;
       this.addChild(shuffleButton);
       shuffleButton.addEventListener(MouseEvent.CLICK, onShuffleButtonClick);
// Clears cell images, shuffles their numbers and then assigns them new images.
private function onShuffleButtonClick():void
   eraseCells();
   shuffleCells(cellNumbers);
   trace("After shuffle: ", cellNumbers);
   for (var i:int = 0; i < cells; i++)
    drawCells(cellNumbers[i]);
// Removes any existing cell images from the display stack.
private function eraseCells(): void
   while (imageArray.numChildren > 0)
    imageArray.removeChildAt(0);
// Shuffles cell numbers (randomizes array).
private function shuffleCells(_array:Array):void
   var _number:int = 0;
   var _a:int = 0;
   var _b:int = 0;
   var _rand:int = 0;
   for (var i:int = _array.length - 1; i > 0; i--)
    _rand = Math.random() * (i - 1);
    _a = _array[i];
    _b = _array[_rand];
    _array[i] = _b;
    _array[_rand] = _a;
// Retrieves and assigns a custom image to a cell based on its numerical value.
private function drawCells(_numeral:int):Array
   var _classRef:Class = Class(getDefinitionByName("skin" + _numeral));
   _classRef.x = 30;
   imageArray.push(_classRef);
   imageArray.addChild(_classRef);
   return imageArray;
===========================================================================
     Any help with this is greatly appreciated. Thanks!

Rothrock,
     Thank you for the reply. Let me address a few things here in the hopes of allowing you (and others) to better understand my reasoning for doing things in this manner (admittedly, there is probably a much better/easier approach to what I am trying to accomplish which is one of the things I hope to learn/discover from these posts).
     The elements inside my "imageArray" are all individual graphics that I had imported, changed their type to movie clips using .Sprite as their base class (instead of .MovieClip) and then saved as classes. The reason I did this was because the classes could then be referenced via "getDefinitionByName" by each cell value that was being passed to it. In this grid every number from 1 to 9 appears randomly 12 times each (making the 108 cells which populate the grid). I did not, at the time (nor do I now), know of a better method to implement for making sure that each image appears in the cell that has the corresponding value (i.e. every time a cell has the value of 8 then the custom graphic/class "skin8" will be assigned to it so that the viewer will be able to see a more aesthetically pleasing numerical representation, that is to say a slightly more fancy looking number with a picture behind it). I was advised to store these images in an array so that I could destroy them when I reshuffle the grid in order to make room for the new images (but I probably messed up the instructions).
     If the "drawCell" function only returns a sprite rather than the image array itself, doesn't that mean that my "eraseCells" function won't be able to delete the array's children as their values weren't first returned to the global variable which my erasing function is accessing?
     As for the function name "drawCells," you have to keep in mind that a) my program has been redesigned in stages as I add new functionality/remove old functionality (such as removing text labels and formatting which were originally in this function) and b) that my program is called "Blanko."
     I will try and attach an Illustrator exported JPG file that contains the image I am using as the class "skin7" just to give you an example of what I'm trying to use as labels (although it won't let me insert it here in this post, so I will try it in the next post).
Thank you for your help!

Deleting an array

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