How to index array in a for loop

i'm connecting from variant-to-data function to an index array function inside a for_loop (refer to attachment). the data-type wire got converted from Table(2-D array) to Table(1-D array). How do I keep it from converting to 1-D array?
Attachments:
arrayI.doc ‏146 KB

Of course it seems you want to run the loop once for each row in the 2D array, so many times autoindexing is the better solution!
You are using an "index array" inside the loop. If you are planning to wire the index to the iteration [i] terminal (who knows? ), you might as well use autoindexing. This way you don't need to wire N (the loop will know how many rows there are) and you don't need to use index array inside the loop.
The image shows two functionally equivalent code fragments. Autoindexing (bottom) is much simpler than explicit indexing (top). See if autoindexing can work in your case.
Since you are a LabVIEW beginner, you should try to stay way from stacked sequences and local variables. They are rarely needed and can ofter cause problems such as race conditions and unreadable code.
Message Edited by altenbach on 03-31-2008 04:17 PM
LabVIEW Champion . Do more with less code and in less time .
Attachments:
autoindexing.png ‏8 KB

Similar Messages

Truncating an array within a for loop

I'm currently working with a program that builds an array of 3000*N real numbers, where N is a control that I specify. I want to pass this array into a for loop that runs N times, each time splitting the first 3000 numbers of the array. So, in other words I want the for loop to execute enough times such that the initial array will be completely divided into groups of 3000 when I'm finished. Later I'll be finding the maximum value of all of these subarrays and taking the average of those. What I tried first is to pass the array into the for loop, then truncate it at index = 3000, but the problem is that I can't hard code the loop to do this N times. Any advice or other methods you'd recommend for doing this?
Thanks.
Message Edited by Robtn on 03-05-2010 03:17 PM

Mark--I don't think I can use that approach. Let me be more specific on what the problem is:
Our "big program" is a giant while loop that constantly reads in voltage values from a DAQ assistant.
It has two modes, the first of which I'm having a lot of trouble with. This mode uses a for loop (N = 3000) nested within the giant while loop.
When the for loop activates, the DAQ assistant takes reads 300 samples for every iteration and takes the maximum of those 300 values. It then builds an array composed of all the maxima. After the for loop has executed 3000 times, a case structure activates, which then finds the maximum of the array of maxima.
I want this (N=3000) for loop to execute an arbitrary number of times, a number that I will specify. Each of those times it should generate a completely seperate array of maxima. So, if I want the for loop to run 5 times, I want 5 different arrays.
My approach for doing this was to change N=3000 to say N = 15000, then split up the resulting array 5 times. So, I need an entirely separate for loop that reads in this array of 15000 maxima on its own and splits it 5 ways. I think what you're suggesting is to use a for loop outside of the N=3000 loop, which is a good idea in theory, but experience has shown that this will not generate 5 separate arrays. It will actually concatenate each array into one, hence the problem we currently have.
Yik--I won't have access to Labview over the weekend. Is it possible to take a screenshot and post it, or maybe a short description?
Thank you for the responses.

How to let " i " of a for loop to start from a "X"

Hi,
how to let " i " of a for loop to start from a value "x" where x is a variable?
Thx
Message Edited by starfish on 10-19-2007 06:00 AM

Hi starfish,
use it like this:
If this doesn't fit your needs you should attach an example of what you really need!
Message Edited by GerdW on 10-19-2007 01:15 PM
Best regards,
GerdW
CLAD, using 2009SP1 + LV2011SP1 + LV2014SP1 on WinXP+Win7+cRIO
Kudos are welcome
Attachments:
I.png ‏2 KB

Transposing data in an array using a For Loop

I am trying to transpose some data in an array using a for loop starting from the size of the array then decrement down to 0. Can someone please help if you have an example?
Solved!
Go to Solution.

I feel as if reverse 1D array may help
Edit: misunderstood what your second post meant.
CLA, LabVIEW Versions 2010-2013

Please help me.. how to rewrite the following java- for loop code in ada

int i, j, n = 100;
for (i = 0, j = 17; i < n; i++, j-- )
sum += i * j + 3;

how to rewrite the following java- for loop code in ada
You should have a programming manual for Ada first. If you mean it the other way round, I think you subject line confused me.

How to traverse an array with a for-loop in this certain way...

so I need to traverse an array starting from the first element, then from the last element, then the second element, then the second last element, then third element and so on... in a for loop
how would that look in code?
Any help would be appreciated, thanks!
Edited by: inspiredone on Apr 4, 2008 6:34 AM

Wow, that's a really clever and elegant way to do it promethuzz. I actually came up with something already before I read your post so yeah don't worry about me copying or anything. Mine is not as elegant/efficient and I definitely like yours a lot more but I will just share it anyway...it looks pretty similar to the second algorithm The_Matrix has provided. I figured this out from thinking how quicksort compares its pivot with the two indexes...
    int front=0;
    int back = a.length - 1;
    int counter =0;
    boolean switchflag = true;
    while(front<=back)
      System.out.println(a[counter]);
      if(switchflag)
        counter = back;
        front++;
        switchflag = false;
      else
        counter = front;
        back--;
        switchflag = true;
    } Anyways, thanks a lot for you guys help, promethuzz, The_Matrix, and newark.
Edited by: inspiredone on Apr 4, 2008 11:25 AM
Edited by: inspiredone on Apr 4, 2008 11:27 AM

How to output last 4 arrays from a For Loop?

Hi People,
I am almost at the end of my tether. I really hope someone could please help me.
Any input would be welcome. VI attached.
VI explanation:
I initialize an array.
The random number generator simulates my camera input.
Depending on which iteration it is, the data is added into one of four output arrays.
'x-y*floor(x/y)' gives a remainder value of 0, 1, 2 or 3.
'Case Selector' just adds 1 to 'x-y*floor(x/y)' to get case 1, 2, 3 or 4.
Shots 1, 5, 9 etc are added to Array 1 (Case 1).
Shots 2, 6, 10 etc are added to Array 2 (Case 2).
Shots 3, 7, 11 etc are added to Array 3 (Case 3).
Shots 4, 8, 12 etc are added to Array 4 (Case 4).
Averaged Output displays the averaged value i.e. the total value divided by the number of shots saved in that array ('Set (IQ+1)').
My problems are:
1) I would like to output only the last 4 sets of data from the Averaged Output 1, 2, 3 and 4 to 4 different files (i.e. save as .csv what is displayed onscreen in indicators 'Averaged Output 1', 2, 3 and 4 at the end of all iterations.
Where should I place my file save diagram disable so that it does this?
Putting it outside the main For Loop with auto-indexing on gives me one file with all previous data. (This is not feasible as my number of shots should number in the thousands)
Putting it outside the main For Loop with auto-indexing off gives me only the last set of data. (I need the output for 4 Arrays, not just the last run)
Putting it inside the main For Loop (as shown) gives me the same number of files as number of iterations. (Again not feasible due to large number of files that will be generated and slow camera capture)
For the sake of fast camera capture, I would like these 4 files to only output once all the image captures are complete.
2) Would preferably like to name the file once and for the programme to append '(1)', '(2)', '(3)' and '(4)' to filename of the appropriate 'Averaged Output' Arrays but file path controls are another big headache for me.
3) P.s. is initializing one array enough to avoid using Memory Manager? Or should I initialize 4 arrays?
I am using Labview 2010.
Thanks so much,
Jaslyn
Solved!
Go to Solution.
Attachments:
Help Understanding Arrays and file paths (10).vi ‏26 KB

Thanks so much Lennard!!
Hi JKSH,
I've been busy trying to complete the dang code, but for completeness so that other users can learn too, I shall answer your queries. Thanks for looking in.
First, what do you mean by "add"? Your code in your case strcuture sums your input values, so your array size doesn't change. However, you also said "Putting it outside the main For Loop with auto-indexing on gives me one file with all previous data. (This is not feasible as my number of shots should number in the thousands)" -- it sounds like you are expecting an array with thousands of elements. So, what should "Output Array N" look like?
Ans: Output Array N should be a 4x4 array of the summation of all the numbers generated during every 4th iteration.
i.e. if random number 1=1, random number 2=2, etc, And 'No of iterations' is 12,
Output Array 1 should be 1+5+9:
15 15 15 15
15 15 15 15
15 15 15 15
15 15 15 15
(Note: Most of your arrays are 4x4, but in Case #2 you created 128x128. I prersume this is a typo?)
Ans: Kind of, I'm using a 4x4 array of randomly generated numbers as an example but my actual data will be the 128x128 pixel output of a camera. And during actual experimentation, 'No of Iterations' will number in the thousands.
Second, why do you add your "simulated camera input" to the "Initialized Array"? You can add it direcly to the previous output inside your case structure.
Ans: See answer to question 3
Third, have a look at shift registers: http://www.ni.com/gettingstarted/labviewbasics/shiftregisters.htm. Use them instead of Feedback Nodes to make your code tidier.
Ans: I did try.. But I can't seem to add shift registers to the case structure, only the for loops outside. Are you sure it can be done..?
jaslyn wrote:
1) I would like to output only the last 4 sets of data from the Averaged Output 1, 2, 3 and 4 to 4 different files (i.e. save as .csv what is displayed onscreen in indicators 'Averaged Output 1', 2, 3 and 4 at the end of all iterations.
Where should I place my file save diagram disable so that it does this?
For the sake of fast camera capture, I would like these 4 files to only output once all the image captures are complete.
You will need to call "Write to Text File.vi" 4 times to write 4 files. So, you should finish your loop, then call this VI 4 times.
Ans: How do I get it to extract the data from each of the 4 cases in my case structure?
jaslyn wrote:
2) Would preferably like to name the file once and for the programme to append '(1)', '(2)', '(3)' and '(4)' to filename of the appropriate 'Averaged Output' Arrays but file path controls are another big headache for me.
You can create strings first, then convert them into paths: http://zone.ni.com/reference/en-XX/help/371361G-01/glang/string_to_path/
Thanks
jaslyn wrote:
3) P.s. is initializing one array enough to avoid using Memory Manager? Or should I initialize 4 arrays?
I'm not sure what you're asking; can you please clarify what you mean by "avoid using Memory Manager"? But anyway, you've actually initialized FIVE arrays: 1 outside the loop, and 1 inside each case.
I've read that to avoid fluctuations in memory usage, it is a good idea to initialize arrays to their expected size before the start of data collection. That was just what I was trying to do.

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 .

I'm creating an array using a for loop, how do I get the values outside the loop while it is running? thanks

I'm creating a set of values using a for loop and a shift register inside the loop. I want access to these values outside the loop as they are being created inside. When I connect a wire from the shift register to a display outside, it doesn't work. How do I do this? Thank you.
Attachments:
tamko_new.vi ‏29 KB

I tried to create the local variable that was wired to numeric indicator inside the loop. If I try to connect this to the analog output outside the loop, the loop just starts blinking and nothing happens, am I doing something wrong? Thanks again.
Attachments:
tamko_new2.vi ‏29 KB

How to maintain counter in a for loop

Hi,
How do we track counter in a loop?Isn't it the way I implemented.? Please suggest.
Regards.
Solved!
Go to Solution.
Attachments:
for loop counter.jpg ‏219 KB

Both loops have errors, if you try to do for(i=60;i<120;i++) you're only running 60 loops, not 120.
You should also disable the autoindexing on incoming arrays as you want some split array indexes (actually you can optimize it by extracting the constant a[30] before the 1st loop and the opposite on the 2nd. Now you're extracting 2 numbers from a 1D array instead of 1 from a 2D array ...
The number on the select/sum function should be integers, no need to calculate doubles.
The small array to sum it up is only max 170 numbers, it's ok although a sum in a shift register would be better.
/Y
LabVIEW 8.2 - 2014
"Only dead fish swim downstream" - "My life for Kudos!" - "Dumb people repeat old mistakes - smart ones create new ones."
G# - Free award winning reference based OOP for LV

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

Passing an array in a for loop to a procedure

I am trying to pass an array in a cursor for loop to a procedure which performs a table insert using the array's contents. Somehow I am missing something, or it is not possible. The compile error states: PLS-00306: wrong number or types in call to 'insert_address' I checked to be sure I am creating the arrays in both cases from similar data objects. Both address and work_address_table contain the same 4 columns with the same data types.
create or replace package work_address as
FUNCTION populate_address return boolean;
procedure insert_address(in_address IN work_address_table%ROWTYPE);
end work_address;
create or replace package body work_address as
function populate_address return boolean is
cursor c1 is
select 'H' as header,
street1 as street
city as city,
NULL as state
from address
where city = 'HANOVER';
TYPE addressT IS TABLE OF c1%ROWTYPE INDEX BY BINARY_INTEGER;
rec1 addressT;
BEGIN
OPEN c1;
FETCH c1 BULK COLLECT INTO rec1 LIMIT 500;
FOR i IN 1..rec1.count LOOP
rec1(i).state := 'US'
insert_address(rec1(i));
exit when c1%notfound;
END LOOP;
CLOSE c1;
return TRUE;
END populate_address;
PROCEDURE insert_address(in_address IN work_address_table%ROWTYPE) IS
BEGIN
INSERT INTO work_address_table
VALUES (in_address.header,
in_address.street,
in_address.city,
in_address.state);
COMMIT;
END insert_address;
END work address;
/

Both address and work_address_table contain the same 4 columns with the same data types.Are you 100% sure about this?
SQL> declare
cursor c1
is
    select 1 deptno, dummy dname, 'Loc' location from dual;
type addresst is table of c1%rowtype
    index by binary_integer;
rec1   addresst;
procedure p (d dept%rowtype)
as
begin
    dbms_output.put_line(d.dname);
end p;
begin
rec1 (1).dname := 'z';
p (rec1 (1));
end;
z
PL/SQL procedure successfully completed.but changing just the first column of the cursor:
SQL> declare
cursor c1
is
    select 'xy' deptno, dummy dname, 'Loc' location from dual;
type addresst is table of c1%rowtype
    index by binary_integer;
rec1   addresst;
procedure p (d dept%rowtype)
as
begin
    dbms_output.put_line(d.dname);
end p;
begin
rec1 (1).dname := 'z';
p (rec1 (1));
end;
Error at line 3
ORA-06550: line 20, column 3:
PLS-00306: wrong number or types of arguments in call to 'P'
ORA-06550: line 20, column 3:
PL/SQL: Statement ignored

Problem cycling through elements of an array using a for loop ~ error 200609?

Hi,
I'm outputting a 194-element array from a MATLAB script node into a for loop where the array is indexed then converted into a 8-bit boolean pattern which I'm trying to output using DAQ Assistant. I'm using LabVIEW 8.2 and a PCI 6133 DAQ using a counter(Ctr0InternalOutput) to time the output. The first element of the array goes through the loop perfectly however never makes it's way back through and throws error 200609: Generation cannot be started because the slescted buffer size is too small. Increase the buffer size. After probing the line before DAQ Assistant I confirmed only one element makes it through the loop and then throws this error? I've trying doing the same things with lower lowel DAQmx vi's using a DAQmx configure output buffer vi to override this buffer size problem, but still get the same result(not the error but same data flow problem)? Anybody know what's going on? I've included the vi's I've been working with. Thanks!
Millie
Attachments:
Untitled 22.vi ‏228 KB
Untitled 34.vi ‏180 KB

Hi,
I'm outputting a 194-element array from a MATLAB script node into a for loop where the array is indexed then converted into a 8-bit boolean pattern which I'm trying to output using DAQ Assistant. I'm using LabVIEW 8.2 and a PCI 6133 DAQ using a counter(Ctr0InternalOutput) to time the output. The first element of the array goes through the loop perfectly however never makes it's way back through and throws error 200609: Generation cannot be started because the slescted buffer size is too small. Increase the buffer size. After probing the line before DAQ Assistant I confirmed only one element makes it through the loop and then throws this error? I've trying doing the same things with lower lowel DAQmx vi's using a DAQmx configure output buffer vi to override this buffer size problem, but still get the same result(not the error but same data flow problem)? Anybody know what's going on? I've included the vi's I've been working with. Thanks!
Millie
Attachments:
Untitled 22.vi ‏228 KB
Untitled 34.vi ‏180 KB

How to pass parameter to cursor for loop having table type?

Hi Friends,
I am wondering how to pass a parameter into second for loop in the example code below.Please see the bold statements and answer my queries.
Thanks a lot .Here is the code .
declare
l_bom_header_tbl BOM_BO_PUB.BOM_HEADER_TBL_TYPE ; ---TABLE TYPE
V_bom_header_tbl Bom_Bo_Pub.Bom_Head_Rec_Type := Bom_Bo_Pub.G_MISS_BOM_HEADER_REC; ---Record type
v_bom_components_tbl Bom_Bo_Pub.Bom_Comps_Tbl_Type := Bom_Bo_Pub.G_MISS_BOM_COMPONENT_TBL;---nested table type
c:=0 number ;
k:=1 number ;
begin
BOMPXINQ.Export_BOM(
P_org_hierarchy_name => l_org_hierarchy_name,
P_assembly_item_name => l_assembly_item_name,
P_organization_code => l_organization_code,
P_alternate_bm_designator => '1Test',
P_Costs => l_costs,
P_Cost_type_id => l_cost_type_id,
X_bom_header_tbl => l_bom_header_tbl,
X_bom_revisions_tbl => l_bom_revisions_tbl,
X_bom_components_tbl => l_bom_components_tbl,
X_bom_ref_designators_tbl => l_bom_ref_designators_tbl,
X_bom_sub_components_tbl => l_bom_sub_components_tbl,
X_bom_comp_ops_tbl => l_bom_comp_ops_tbl,
X_Err_Msg => l_Err_Msg,
X_Error_Code => l_Error_Code);
if l_Error_Code = 0 then
for i in 1 .. l_bom_header_tbl.COUNT LOOP
V_bom_header_tbl.organization_code :='DSC';
Can we assign a table type to record type like below statement?
V_bom_header_tbl.assembly_item_name:= l_bom_header_tbl(i).assembly_item_name ;
k:=1;
I want to pass parameter l_bom_header_tbl(i).assembly_item_name into the for statement below: How to achieve this?
for j in 1 .. l_bom_components_tbl.COUNT LOOP
Can we assign a table type to table type like below statement?
v_bom_components_tbl(k).Assembly_Item_name := l_bom_header_tbl(i).assembly_item_name ;
k := k + 1;
end LOOP;
end loop;
end;
Edited by: ILovePlSql on Mar 22, 2010 7:51 AM
Edited by: ILovePlSql on Mar 22, 2010 8:16 AM

ILovePlSql wrote:
V_bom_header_tbl.assembly_item_name:= l_bom_header_tbl(i).assembly_item_name ;
v_bom_header_tabl is a record type and l_bom_header_tbl is a table type .So is the above statement ok?I asked you for type definition. Please provide definition of BOM_BO_PUB.BOM_HEADER_TBL_TYPE and Bom_Bo_Pub.Bom_Head_Rec_Type. If BOM_BO_PUB.BOM_HEADER_TBL_TYPE is table of Bom_Bo_Pub.Bom_Head_Rec_Type then your statment is OK. For example:
SQL> declare
2      type BOM_HEADER_TBL_TYPE is table of emp%rowtype index by binary_integer;
3      l_bom_header_tbl BOM_HEADER_TBL_TYPE;
4      V_bom_header_tbl emp%rowtype;
5 begin
6      select * bulk collect into l_bom_header_tbl from emp;
7      for i in 1 .. l_bom_header_tbl.count loop
8        V_bom_header_tbl.ename := l_bom_header_tbl(i).ename;
9      end loop;
10 end;
11 /
PL/SQL procedure successfully completed.
SQL> SY.

Creating an array in a 'for' loop (resetting loop count)

Hi,
I am trying to integrate an acceleration signal coming from a CRIO analogue input to obtain the speed and then further integrate to get the displacement of a vibration system.
I understand that in order to perform the integration, an array has to be fed in. My problem is that I could not buffer the signal in a buffer block as I couldn't find any buffer blocks. so I decided to create my an array of data using a 'for' loop. The 'for' loop nests inside a timed loop. The problem that I got stuck at is how to reset the 'for' loop in order to refill the buffer again at every iteration of the outer timed loop.
I have attached the code if that helps. Note that I am using labview 2013.
I would be gratefull if someone who had encountered a similar issue before can help me.
Regards
Ali
Solved!
Go to Solution.
Attachments:
acc_test.vi ‏42 KB

Dear Altenbach,
Many thanks for your reply.
I need to make it clear that I have not had enough hands-on with labview, I have only used it for sometime in the past and now I have to in order to perform some active damping on a 50Hz running machine. I must stress the fact that what i find more intuitive to do in a different programming language (matlab or C) is not as straightforward in labview. so please bear with me if my code has basic mistakes .
All what i am trying to do is obtain the speed and position from an acclerometer signal. unfortunately i dont have a position sensor so i have to measure acceleration then perform time integrations in order to obtain the speed and position respectively. I am using a compact Rio (later in FPGA mode) to take physical measurements of acceleration from the vibratory machine and where i managed to do this bit successfully. when it came to performing the integration, i had to create an array inside my timed loop since i couldn't find a buffer block. I implemented a 'for' loop inside a timed loop in order to build the array. however i got stuck at resetting the count of the 'for' loop in order to refill the array with new values at every new iteration of the outer timed loop. unfortunately, even a sensible answer has been suggested before, i dont seem to have been capable of doing it yet. I really spent all my day trying to figure a way out but not achieved it yet, nevertheless I have learnt many many things by playing around.
I would be gratefull if you could comment on a possible way of doing what i am trying to do.
Kind Regards
Ali

How to index array in a for loop

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