For loop indexing?

Is it possible to change indexing step in labView "For Loop" structure? By
default this value is 1, and I need to make a step value different from "1"
like in C example:
for (index=0; index < 100; index++) {}; // step=1
for (index=0; index < 100; index=index+3) {}; // step=3
Sergey Yakovlev, Berlin,
[email protected]

Hallo, Sergey,
Du (yakovlev) meintest am 21.09.01 zum Thema for loop indexing?:
> Is it possible to change indexing step in labView "For Loop"
> structure? By default this value is 1, and I need to make a step
> value different from "1" like in C example:
> for (index=0; index < 100; index++) {}; // step=1
> for (index=0; index < 100; index=index+3) {}; // step=3
What about
j:=i*3
and i is incremented by 1
Greetings!
Helmut
Please excuse my gerlish!

Similar Messages

Using a For Loop Index for Array Element Number?

Hi. Thanks in advance for the help. I can't seem to find what I want to do here using the search function... probably because I don't know how to frame the question appropriately. Ignore the title to this post cause it's probably wrong vocabulary for what I want to do.
Here's the situation:
I have a 2D array where the first column is the X data and each subsequent column is Y data (call it Y1...Yn). The n-value varies from run to run (some runs have 4 columns of data, some have 20), but that is easily gathered when reading the data file. I need to perform a number of operations on each set of data, the least of which is smoothing the data and graphing it, so I'm limiting my discussion to these 2 operations.
What I want is a for loop structure where the indexing of the loop tracks the Y1...Yn columns, grabs each column for the iteration, performs the relevant analysis, and spits out the result, but in a stackable manner. Thus the title; I want to use the for loop's index to mark the array element for building a new array.
See the image attached. A 2D array of 9 columns (X, Y1...Y8) is analyzed such that each data set, (X, Y1), (X, Y2)...(X, Y8) is bundled, graphed, run through a B-spline Fit, of which is also graphed. I need to replace this with something that looks like the for loop structure shown.
I just don't know how to get those two data bundles [(X, Yi) and it's smoothed pair] out of the for loop in a stacked set from every iteration of the for loop.
Again the title, I think I want to build a new array where i use the index of the for loop to control the entries of the new array. But I can't see how to do that.
Any help would be appreciated.
Attachments:
NeedForLoopForThis.PNG ‏30 KB

Hello H.R. Dunham, and welcome to the forum!
It seems that you may be looking for Auto-Indexing, a basic feature of loops in LabVIEW. You'll need to transpose your array before wiring it into the for loop, as elements are auto-indexed by row before column, but at that point you should be able to operate on each column and output an array of n cluster elements corresponding to your input columns. Auto-indexing tunnels look like brackets to indicate each element will be indexed automatically- this should be the default when wiring an array into a for loop or when wiring anything out of a for loop.
As for how to build your pairs, I suggest removing the X column and creating a "starter" cluster containing your X data and placeholder Y data before entering your "Y" processing loop. Use the bundle by name function in the for loop to insert your processed column data into the cluster and auto-index the cluster output. Flow would be something like this:
1) Gather data
2) Split X and Y using standard array operations
3) Create "template" cluster with shared X data
4) Pass template cluster and Y-column array into an auto-indexed for loop.
5) Insert processed Y data into cluster inside loop.
6) Auto-index cluster data out of loop.
This tutorial is probably also a good place to get started:
Getting Started with NI LabVIEW Module 3: Loops
http://www.ni.com/white-paper/7528/en/
Hope that helps!
Regards,
Tom L.

For loop pause till event occurs

I'd like to know if it's possible pausing for loop in a fixed step till en event occurs.
I need to use for loop index to indexing some vector's data, but the steps in for loop must be exectuted only if precise condition occurs.
thank you very much for possible solutions
Francesco

Without seeing any code, it is hard to recommend what to do.
You probably want a State Machine architecture so that you can stay in a certain state of a while loop, then move on to the next step (state) when your condition is met.
You could also use event structures. You could also use notifiers or occurrences to hold the execution of your loop until the notifier is written to or occurrence executed in a parallel loop of your code.

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

Tons of ieq/add/or instructions for array indexing in pixel shader loop (D3D 11.0, PS model 5.0)

First of all, I have to apologize for the long code samples, but their content is not so important, I just wanted to give as much info as I can. Besides they are really simple and I tried to comment as much as possible.
I'm working on a pixel shader doing deferred lighting of the frame (Direct3D feature level 11.0, PS
model 5.0, IDE - Visual Studio 2013, OS - Windows 8.1 x64). I noticed some huge FPS drops when I add light sources to the scene, and the more sources I add, the bigger performance impact is. After many hours
of trying to find the problem, experimenting and checking compiled pixel shader ASM's, I found out that at some moment after I comment / uncomment some lines (or event line) my output ASM changes dramatically. I won't put here all the code, of course, but
here's simplified part of the point lighting in HLSL, so you could imagine the structure of the lighting algorithm:
// Total amount of color that pixel receives from all the point light sources.
float3 totalPointLightColor = { 0.0f, 0.0f, 0.0f };
// Loop through the active light sources.
[loop] for (uint i = 0; i < g_scene.pointLightCount; i++)
// xyz - vector from light source to pixel.
// w - the length of that vector.
float4 fromLightToPixel;
fromLightToPixel.xyz = worldPos - g_pointLights[i].position.xyz;
fromLightToPixel.w = length(fromLightToPixel.xyz);
// Check max light distance here (skip pixel if it is too far).
if (fromLightToPixel.w > g_pointLights[i].farZ)
continue;
// Normalize direction vector.
fromLightToPixel.xyz = normalize(fromLightToPixel.xyz);
// Angle between the pixel normal and light direction.
float lightIntensity = saturate(dot(normal, -fromLightToPixel.xyz));
// Check that light comes not from behind of the pixel surface.
if (lightIntensity <= 0.0f)
continue;
// If light casts shadows, process shadow map and get amount of light the pixel receives.
// THIS LINE IS MENTIONED IN MY QUESTION BELOW.
if (g_pointLights[i].shadowMapIndex >= 0)
// Here was shadow map check, but I removed it and nothing really changed - the problem remained even with no code here.
// Calculate the amount of light at the pixel from distance and angle and modify intensity.
lightIntensity *= g_pointLights[i].brightness / (fromLightToPixel.w * fromLightToPixel.w);
// Add this light's color to the total amount of light the pixel receives from point lights.
totalPointLightColor += lightIntensity * g_pointLights[i].color.rgb;
I compile shaders with D3DCompileFromFile() method, using the following flags:
shaderFlags = D3DCOMPILE_ENABLE_STRICTNESS | D3DCOMPILE_DEBUG
| D3DCOMPILE_SKIP_OPTIMIZATION | D3DCOMPILE_PREFER_FLOW_CONTROL;
I tried to compile in release config with the following flags:
shaderFlags = D3DCOMPILE_ENABLE_STRICTNESS | D3DCOMPILE_OPTIMIZATION_LEVEL3;
But nothing seriously changes - only a couple less ASM instructions here and there, the main problem still remained. I should add that I have zero to none knowledge of ASM, and understand what's happening mostly thanks to comments Visual Studio / FXC generates
in debug compilation mode.
So, when I compile my whole deferred shader (including the part above), I get
414 instructions in ASM, and performance is fine. If I uncomment only 1 line with CAPSED comment in the section above (which actually does nothing, as you can see), I get
476 instructions, and I get huge FPS hiccups. When I check output ASM code, I can clearly see, that the line I uncommented produces no code in ASM at all, but somehow it makes many parts of compiled shader to change.
For example, the loop above with commented line looks like the following in ASM:
# Loop starts.
loop
# Loop index check and increment, as I can understand.
uge r6.w, r5.w, cb0[1].x
breakc_nz r6.w
imul null, r6.w, r5.w, l(3)
# Calculate <fromLightToPixel>.
# cb6 - constant buffer that stores point lights.
# Array access is done simply via [] operator.
add r10.xyz, r3.xyzx, -cb6[r6.w + 1].xyzx
dp3 r7.w, r10.xyzx, r10.xyzx
sqrt r8.w, r7.w
# Distance check.
lt r8.w, cb6[r6.w + 1].w, r8.w
if_nz r8.w
iadd r8.w, r5.w, l(1)
mov r5.w, r8.w
continue
endif
# Normalization.
rsq r8.w, r7.w
mul r10.xyz, r8.wwww, r10.xyzx
# Calculate <lightIntensity>.
dp3_sat r8.w, r1.xywx, -r10.xyzx
# Check <lightIntensity>.
ge r9.w, l(0.000000), r8.w
if_nz r9.w
iadd r9.w, r5.w, l(1) // r9.w <- i
mov r5.w, r9.w // r5.w <- i
continue
endif
# Update <lightIntensity>. Note [] operator.
div r7.w, cb6[r6.w + 0].w, r7.w
mul r7.w, r7.w, r8.w
# etc.
endloop
When I
uncomment that 1 line, the ASM is growing heavily (by 62 instructions!), and this is how it starts to look like:
# Loop starts.
loop
# Loop index check, but no <imul> instruction, why?
uge r6.w, r5.w, cb0[1].x
breakc_nz r6.w
# Here comes some new code...
# Indices are obviously related to the size of the point lights' constant buffer (16 elements).
ieq r10.xyzw, r5.wwww, l(0, 1, 2, 3)
ieq r11.xyzw, r5.wwww, l(4, 5, 6, 7)
ieq r12.xyzw, r5.wwww, l(8, 9, 10, 11)
ieq r13.xyzw, r5.wwww, l(12, 13, 14, 15)
# And this part is also new...
and r14.xyzw, r10.xxxx, cb6[1].xyzw
and r15.xyzw, r10.yyyy, cb6[4].xyzw
or r14.xyzw, r14.xyzw, r15.xyzw
and r15.xyzw, r10.zzzz, cb6[7].xyzw
or r14.xyzw, r14.xyzw, r15.xyzw
# 26 more lines of such and/or pairs.
# Calculate <fromLightToPixel> - finally! Why so much code instead of simple [] operator?
add r14.xyz, r3.xyzx, -r14.xyzx
dp3 r6.w, r14.xyzx, r14.xyzx
sqrt r7.w, r6.w
# Distance check.
lt r7.w, r14.w, r7.w
if_nz r7.w
iadd r7.w, r5.w, l(1)
mov r5.w, r7.w
continue
endif
# Normalization.
rsq r7.w, r6.w
mul r14.xyz, r7.wwww, r14.xyzx
# Calculate <lightIntensity>.
dp3_sat r7.w, r1.xywx, -r14.xyzx
# Check <lightIntensity>.
ge r8.w, l(0.000000), r7.w
if_nz r8.w
iadd r8.w, r5.w, l(1)
mov r5.w, r8.w
continue
endif
# Here we go again - more code!
and r15.xyzw, r10.xxxx, cb6[0].wxyz
and r16.xyzw, r10.yyyy, cb6[3].wxyz
or r15.xyzw, r15.xyzw, r16.xyzw
and r16.xyzw, r10.zzzz, cb6[6].wxyz
or r15.xyzw, r15.xyzw, r16.xyzw
# 26 more lines of such and/or pairs.
# Update <lightIntensity> - finally! Why no [] operator here, but tons of those instructions?
div r6.w, r10.x, r6.w
mul r6.w, r6.w, r7.w
# etc.
endloop
I tried to save current array element to temp variable at the beginning of the loop, but it makes no difference - only several more instructions are added to copy the data.
I just can't understand, why in the first case loop is translated into such small and logic code where array access is done via single
[] operator, but in the second one it expands to such enormous bunch of instructions? And I change only 1 line of code, nothing more (and that line does nothing actually - it even has no ASM representation)! But every array access seems to
be affected with this change.
Can someone please explain that to me? Is there some sort of tricks with array indexing or loops in HLSL? I tried to find something about it on the Internet to no avail. Seems like I miss something very simple and obvious, but I don't get it. Sadly I
work mostly alone by now and know nobody familiar with ASM / HLSL / Direct3D. Answering this question on another popular developer resource brought no result.
Big thanks in advance for any tips or explanations!

The latest version may help with this. 11.9.900.170 is now a step back.
12.0.0.38 is here: http://get.adobe.com/flashplayer/
or download the FULL installer here: Flash Player 12 (Mac OS X)

Why are date and time strings lost when indexing an array in a for loop

Hi,
I have an application where i'm reformatting data from a spreadsheet for graphical display on a LabVIEW dashboard.
the original spreadsheet has date and time values in separate columns, and i'm merging them and converting to a timestamp value. But something's not working. Does anyone know why the string value is lost when the array indexes into this for loop?
Attachments:
failed array index.png ‏142 KB

Can you attach your VI with some typical values? (e.g. create in indicator on the 2D array, run your VI, then turn the indicator (now containing data) into a diagram constant). Place the FOR loop related code and that diagram constant into a new VI and attach it here.
How many times does the FOR loop run? Could it be that the last element of each 1D array is an empty string? (unless you put a wait inside the FOR loop, you'll never see the other elements in the probe)
LabVIEW Champion . Do more with less code and in less time .

Indexing data on a for loop to overlay data on a xy graph

I am using express VI's to measure both voltage and current data in a For Loop. I want to plot a current vs voltage graph but have each iteration of the loop overlay the others as if it were its own independent data set. I have been unable to bundle the data and convert it into a xy graph because of the number of elements, 3 for the bundle and 2 for the graph. I need a method to index the dynamic data wires so that I can overlay them.

Hello,
After reading the thread, it sounds like you're looking for a chart-like graph - I have attached an example with illustrates this. Keep in mind that "graphs" in LabVIEW generally plot arrays of data (in the case of an XY graph, you pass a cluster which contains an X and Y array). The example behaves like a chart by building an array one data point at a time (in this case both an X and Y array of course) on each iteration of a loop, and displaying the data at each loop iteration - this gives the look and feel of a chart which accumulates data. It is attached in version 7.1 - hopefully you have that version or later to open it. I have also attached a program which shows how to plot multiple data sets on an XY graph, in all 3 current formats accepted by the XY graph - it's attached in version 8.0 because the ability to plot complex data to an XY graph was added to version 8.0, and it illustrates this as well.
Best Regards,
JLS
Best,
JLS
Sixclear
Attachments:
XY Chart-like Example.vi ‏24 KB
XYGraphWithArbitrarilyManyPlots.vi ‏32 KB

Index out of Bounds Exception in for loop.

Occasionaly with the code below, i get an index out of bounds error, index 1, size 1, however the for loop should ensure that it never calls the getActorLocation method if the index is the same size as the arrayList size.
Im having one of those days, and i just cant see what error i have made.
Perhaps i need coffee? lol
Cheers
James
private void checkMemoryIntegrity(){
        Actor actor = actorList.get(actorIndex);
        ArrayList<Integer> inRangeList = getActorsInMemoryRange(actor, actor.getRange());
        inRangeList.trimToSize();
        for (int i = 0; i < inRangeList.size();i++){
            if (inRangeList.size() != 0){
                actor = brainState.getActorLocation(i); //<<<<<<<<< problem line
                if (!actorList.contains(actor)){
                    brainState.actorLocations.remove(i);
public ArrayList <Integer> getActorsInMemoryRange(Actor actor, int range){
        int i = 0;
        int x = actor.getX();
        int y = actor.getY();
        ArrayList <Integer> inRangeList = new ArrayList <Integer> ();
        Actor compActor;
        while (i< brainState.actorLocations.size())
            compActor = brainState.getActorLocation(i);
            int xDist = x - compActor.getX();
            if ( (xDist >= (-1) * range) && (xDist <= range) ){
                int yDist = y - compActor.getY();
                if ( (yDist >= (-1) * range) && (yDist <= range) ){
                    inRangeList.add(i);
            i++;
        return inRangeList;
    }

I was thinking it might be easier to do it this way:
Iterator<Actor> i = actorLocations.iterator();
while(i.hasNext())
    if (!actorList.contains(i.next())) {
        i.remove();
}It sounds like you have an equals() method which compares the x and y locations of the actor. If not then you will have to enclose the remove in an if block which compares the actor location. Does that make sense?
Edit: contains uses the equals method.
Returns true if this list contains the specified element. More formally, returns true if and only if this list contains at least one element e such that
(o==null ? e==null : o.equals(e)).Edited by: Edward_Kimber on May 23, 2008 11:43 AM

For loop array index not from 0

HI!
I have an array that is wired into a For Loop. Inside the For Loop there is already a single Array content available as there is this autoindexing feature (?). I do want to change the Array from a certain position different from 0 onwards to the end e.g. change positions 4, 5 and 6 in a for loop executing 3 times. But the for loop and the autoindexing feature start at 0. Can I change this in an elegant way. At the moment I'm running thru the hole array and begin changing at a certain position.

Yes, disable autoindexing on the tunnel and use "index array" inside the loop. Use [n]+4 as index and wire a "3" to the loop count in your particular example.
If you want to keep the entire array and just replace a few elements with updated values, the array needs to be fed in via a shift register. Write the new elements at the desired position using "replace array subset" (see attached very simple example).
LabVIEW Champion . Do more with less code and in less time .
Attachments:
ReplaceSomeArrayElements.gif ‏3 KB

How to index a array to give it to for loop for one value at a time sequence to be ensured

I need to give one number from a array at a time to a for loop. means the for loop have to execute one number at a time from a array of numbers. How to do it

Ranjeet,
Ranjeet_Singh wrote:
But question is same only. is in it ?
With all due respect, NO.
Please make sure you know what you are talking about before blatantly countering someone else's comment. Can you prove that your vi and TiTou's snippet will do the same thing?
Beginner? Try LabVIEW Basics
Sharing bits of code? Try Snippets or LAVA Code Capture Tool
Have you tried Quick Drop?, Visit QD Community.

Conditionally Indexed For Loop Terminal

Dear LabVIEW community!
Most of you, I’m sure, know and use in LabVIEW 2012 such useful and helpful feature as conditional terminal in For Loop (see it on the picture below).
But if one saves such code in previous versions of LabVIEW, then we see, that code has different look (VI Snippet was made in LV 2012, so don’t be confused – it is really code in LV 2011).
The same algorithm is made by using case structure and shift register. But the problem is that this shift register is uninitialized (1) (we have some constant (2) on the block diagram after saving file in previous version, but it is wrong constant for our case), and you know, that it can cause unexpected behavior of the program. So, if you have to convert such a code to previous versions of LabVIEW, don’t forget to check it, and initialize that shift registers.
Solved!
Go to Solution.

Wow! I had no idea this little "conditional terminal" existed. I've been doing Example B all this time, and it sometimes really causes my BDs to elongate. I don't know about you, but my programming always to contain the best examples of "The drawing will fill the space available - and then some." Now, I'll get to stick in one or two more bits before I hit the right-hand wall. Thanks.
Cameron
To err is human, but to really foul it up requires a computer.
The optimist believes we are in the best of all possible worlds - the pessimist fears this is true.
Profanity is the one language all programmers know best.
An expert is someone who has made all the possible mistakes.
To learn something about LabVIEW at no extra cost, work the online LabVIEW tutorial(s):
LabVIEW Unit 1 - Getting Started
Learn to Use LabVIEW with MyDAQ

Loops index

I installed Apple Loops for Soundtrack Pro but the loops do not appear in the loops browser in Logic. The search index.txt file is missing from the Apple Loops Index folder. How can I fix this problem?

found the solution, simply drag the folder onto the loops browser, that indexes the loops!

Is there a routine one can use to shift the column of data by one each time the loop index increments? In other words, increment the columns that the data is being saved by using the index?

The device, an Ocean Optics spectrometer in columns of about 9000 cells.I'm saving this as a lvm file using the "write to measurement file.vi". But it doesn't give me the flexibility as far as I can tell.
I need to move the column by the index of the for loop, so that when i = n, the data will take up the n+1 column. (the 1st column is used for wavelength). How do I use the "write to spreadsheet file.vi" to do this? Also, if I use the "write to spreadsheet file.vi", is there a way one can increment the file name, so that the data isn't written over. I like what "write to measurement file.vi" does.
I'd really appreciate any help someone can give me. I'm a novice at this, so the greater the detail, the better. Thanks!!!

You cannot write one column at a time to a spreadsheet file, because a file is arranged linearly and adding a column would need to move (=read and rewwrite elsewhere) almost all existing elements to interlace the new data. You can only append new rows without having to touch the already written data.
Fields typically don't have fixed width. An exception would be binary files that are pre-allocated at the final size. In this case you can write columns by setting the file positions for each element. It still will be very inefficient.
What you could do is append rows until all data is written, the read, transpose, and write back the final file.
What you also could to is build the final array in a shift register and write the entire things to file at once after all data is present.
LabVIEW Champion . Do more with less code and in less time .

Getting the label of a JButton in a for loop

hi,
I doing a project for my course at the minute and im in need of a bit of help. I have set up 1-d array of buttons and i have layed them out using a for loop. I have also added an annoymous action listener to each button in the loop. It looks something lke this:
b = new JButton[43];
for (int i=1; i<43; i++)
b[i] = new JButton(" ");
b.addActionListener(
new ActionListener()
public void actionPerformed(ActionEvent e)
          System.out.println("..........");
}); // addActionListener
} // for
I want the "System.out.println( ..." line, to print out the "i" number of the button that was pressed but i cannot figure out how to do it. I cannot put "System.out.println(" "+i);" as it wont recognise i as it is not inside the for loop. Does anyone have any suggestions?
Thanks!!

class ButtonExample extends JFrame implements ActionListener{The OP wanted to have anonymous listeners, not a subclassed JFrame
listening to the buttons. I don't know if the following is the best design,
since the poster has revealed so little, but here is how to pass the
loop index to an anonymous class.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class ButtonExample {
    private JButton[] buttons = new JButton[24];
    public JPanel createGUI() {
        JPanel gui = new JPanel(new GridLayout(6, 4));
        for(int i=0; i<buttons.length; i++) {
            final int ii = i; //!! !
            buttons[i] = new JButton("button #" + i);
            buttons.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent evt) {
System.out.println("number " + ii);
gui.add(buttons[i]);
return gui;
public static void main(String[] args) {
ButtonExample app = new ButtonExample();
JPanel gui = app.createGUI();
JFrame f = new JFrame("ButtonExample");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.getContentPane().add(gui);
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);

How to ignore error and continue with next value in PL/SQL FOR loop?

hi,
When the DROP INDEX statement fails it have to continue with the next value in FOR loop without exiting from the loop. Can anyone tell me how to do this?
DECLARE
CURSOR aud_cur IS
SELECT key_col_idx FROM audience_work where aud_ref_id between 106 and 109;
BEGIN
FOR aud_row IN aud_cur LOOP
EXECUTE IMMEDIATE
'DROP INDEX ' || aud_row.key_col_idx;
END LOOP;
END;
Thanks,
Noble

DECLARE
CURSOR aud_cur
IS
SELECT key_col_idx FROM audience_work where aud_ref_id between 106 and 109;
BEGIN
FOR aud_row IN aud_cur LOOP
    begin
      EXECUTE IMMEDIATE 'DROP INDEX ' || aud_row.key_col_idx;
    exception
      when others then
        if sqlcode = -01418 then
          dbms_output.put_line(' index does not exist ');
        else
          dbms_output.put_line(sqlcode);
          raise;
        end if;
    end;
END LOOP;
END;
/

For loop indexing?

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