Write arrays to file

Hi,
I want to write some arrays into a file side by side.
Like that..
A B C D
1 0,25 0,4 0,25
2 0,36 0,3 0,96
Hox can i do it?
Thanks a lot..
irfan

The question is how you want to read the saved data.
- If you want to be able to open the file in a text editor or Microsoft Excel, then you should save the 2D-array as ASCII-characters - easiest example is to use the "Write To Spreadsheet File.vi" from the "File I/O" palette.
- If you only want to read the file from LabVIEW then the most efficient method is to save as binary data. Here is an excellent KnowledgeBase that shows this concept.
Please notice that saving your data as binary data makes it impossible for you to open it in Excel.
Best regards,
Philip C.
National In
struments
- Philip Courtois, Thinkbot Solutions

Similar Messages

Write array to file

Hi,
i am trying to write an array coming out of a for loop into a file. If i plot the array in the Front panel everything works, but if i write it to a text file some aditional characters (empty space and this rectangle) appear.
The file should look like the text file but without spaces before first number of row and rectangle.
Attached are .txt and screenshot of blockdiagramm
Thanks for any help
Philipp
Attachments:
bd.jpg ‏98 KB
summary.txt ‏1 KB

First of all: Thanks.
Your solution did exactely what i want, and i am fine with using a non-elegant version, if it works.
About that autoindexing + indexing the path:
I know this is stupid, and i changed it to not autoindexing. But these things happen, when you try to quickly expand an already existing vi and want to automatize with for loops instead of doing the same things over and over.
I am attaching the whole vi. it first was just the analysis, basically the inner loop, where i wanted to be able to vary the number and size of the parts of the waveform that go into the PSD to see how analysis time and numbers of averages effects the spectrum.
In the next step i created a vi that writes a string of two variables in a file, and then i wanted to do this for all files in a directory.
i am totally aware of the fact, that there are several dirty solutions. But i guess you are used to seeing these things, that could be done much more elegantely and efficiently, but if you try to get a quick solution that works for you and you learned Labview by trial and error, this is the way your vi´s look like.
By the way, what would you suggest to learn "clean" labVIEW programming ?
thanks again,
Philipp
Attachments:
acc_analysis+summary+loop.vi ‏182 KB

Write arrays into a text file in different columns at different times

Hi,
I have a problem write data into a text file. I want to write 4 1D arrays into a text file. The problem is that I need to write it at different time and in different column (in other word, not only append the arrays).
Do you have an idea to solve my problem?
Thank you

A file is long a linear string of data (text). In order ro insert columns, you need to rewrite the entire file, because colums are interlaced over the entire lenght of the file.
So:
read file into 2D array
insert columns using array operations
write resulting 2D array to file again.
(Only if your colums are guaranteed to be fixed width AND you know the final number of colums, you could write the missing columns as spaces and then overwrite later. Still, it will be painful and inefficient, because column data are not adjacent in the file.)
LabVIEW Champion . Do more with less code and in less time .

Save 2D array in write to spreadsheet file

Hello,
I want to save 2 signals coming from 2 channels in 1 file ( as a 2D file:
column 1 for signal coming from channel 1, and column 2 for signal coming from channel 2).
How I can do it?
See my example please. I can save these 2 signals on 2 different files. I
can not find a way to put them in on file.
Thank you so much.
Pascal
Attachments:
2 signal save.vi ‏80 KB

Since the output of AI Read is a 1D array of waveforms you have to extract the data of each waveform and create a 2D array in order to feed that to the Write to Spreadhsheet File VI:
You'll need to check on the transpose. Note that doing this will lose the timing information. You may want to use the Write LabVIEW Measurement File Express VI instead.
Also, any reason why you have a loop set to run just once?
Message Edited by smercurio_fc on 03-19-2008 03:16 PM
Attachments:
save 2D.png ‏3 KB

I want to sample syncronously an analog and digital channel and write them to file in array.

I have a PCI-MIO-16XE-10. I am using the AI01 and a DI01 to recieve the signals. I am monitoring and switch and want to know when it comes on in relation to my analog signals when I post process the data so it is important that the signals be synced and placed in the data array. The attatched vi gives some idea of what I want to do. Thank you in advance for help concerning this.
JML
Attachments:
DigitalAnalogSample.vi ‏34 KB

I am using 6221 same issue i have .
i need to accuire pulse of train and its simaltanously triggering the AI.
Issue is while writing this data to an Excel sheet i am missing some data in-between.
number of pulses are 870 , this count i am getting incermentally in the output of Counter
i did "build an array" with this AI and Counter data and writing it to file, there i misses data.
Attached wiring diagram for reference.
Pls suggest some method to write data to file for every pulses so that i wont miss any data.
Joe
Using Ver. 8.0
Attachments:
Wiring1.JPG ‏137 KB

Write to spreadsheet file.vi is storing data in one row only.

The 8 points of data is going into one column in the spreadsheet. In the "Write to spreadsheet file string.vi" how do I write the 8 points to one row for each cycle?
I got this VI from NI's web a couple of years ago and forgot how to modify this part. I usume it is within the write file.vi.
Thank you in advance
Skip

I just reread your original post and the way the "Write to Spreadsheet File.vi" that ships with LV works by default is to put 1D arrays into rows. I read your post backwards and told you how to put the data in a column. Sorry.
In any case, perhaps you need to make sure the Transpose input ISN'T true, and that the delimiter IS a tab.
Mike...
Certified Professional Instructor
Certified LabVIEW Architect
LabVIEW Champion
"... after all, He's not a tame lion..."
Be thinking ahead and mark your dance card for NI Week 2015 now: TS 6139 - Object Oriented First Steps

Labview 9.0: Error 1 occurred at Write To Measurement File

Hi
Our University recently got the latest version of Labview (9.0 32-bit) which I installed today.The labview file I am using (my6008v6.vi) used to work fine with the older version (8.5 i think). My write-to-file VI is enabled at certain time intervals in order to log data. As soon as it is enabled for the second time I get the following error:
Error 1 occurred at Write To Measurement File->Copy of murray6008v6.vi
Possible reason(s):
LabVIEW: An input parameter is invalid. For example if the input is a path, the path might contain a character not allowed by the OS such as ? or @.
=========================
NI-488: Command requires GPIB Controller to be Controller-In-Charge.
I made a simple file (simplew2f.vi) to test this, with a button which I can press to enable/disable the writing of data. I am able to start writing data and then stop writing data but as soon as I try resume the writing the same error occurs.
This confuses me greatly since this wasn't a problem using the old version and my Labview knowledge is minimal. Any help would be appreciated.
Attachments:
my6008v6.vi ‏214 KB
simplew2f.vi ‏64 KB

So, which VI are you having problems with? Sounds like both...
Okay... - sigh - where to start....
Well.. Let's start with a few comments.
1. Try to stay away from the Express VI. I know the Marketing guys at NI will not like me for saying so, but I am saying so. They are a nice marketing feature that Grumpy Old Men like myself do not like. They make it easy to write quick code.. And I will limit my comments to that. (It's not your fault.. )
2. The wiring on your diagram is not clear or easy to read. Yes, with additional time and double-clicking each wire I can tell where they are going. However, a rule of thumb, alway wire from Left to Right. Never right to left. And do not run the wires under objects, even the ones you are wiring to.
3. simplew2f.vi: You should put a small delay in the While Loop. I ran it three times and it wrote to the files without error. And yes, I used LV2009.
4. my6008v6.vi: Avoid wiring from the top of the While Loop. At frist, it looked like the data was coming out of the While Loop because the wires went to the left side of all the index node of the Index Array function.
You should set your Browse Option for the file path to "Files or Folders" and "New or existing". I did that and I was not getting the error message you described.
R
Message Edited by Ray.R on 03-03-2010 08:33 AM
Attachments:
pathProperty.PNG ‏13 KB

Write to Text File.vi Output file all but first line start with tab

The attached PNG shows the code used to build up concatenated strings into a string array for the first four lines, thence to a string Array, to Spreadsheet String.vi and, finally, the use of Write to Text File.vi
The lower right corner shows the result loaded into a spreadsheet. Note the 3 blank entries marked by a filled red rectangle. Examination of hidden characters shows there is a tab at the beginning of lines 2, 3 and 4.
There is no tab shown in the code. How do those tabs get there? How do I stop them?
I have tried with the option "Convert EOL" both on and off with no difference.
The Help states that an OS-dependent EOL character is appended to each line. I can't imagine the Windows EOL character includes a tab.
Solved!
Go to Solution.
Attachments:
Tab Mystery.PNG ‏29 KB

wildcatherder wrote:
I am still puzzled as to why those additional tabs were added by Array to Spreadsheet String. I'm holding in my hand a printout of an old LabVIEW 8 program with that construction, which is known to work properly.
Makes complete sense when you look at your code. You build a string, including an end-of-line character, and put that string into an array. Then, when you run it through Array to Spreadsheet String, it puts a tab after every array element, and new line at the end of each row in the array. The first element of your array contains a new line but Array to Spreadsheet String doesn't know about it; it still inserts a tab between that array element and the next one, giving you the tabs.

Bug in LV8 : 'Save for previous version' and 'Write to Binary File' VI

Hello
I am using LabVIEW 8's revamped 'Write to Binary File' VI with a 'TRUE' boolean constant wired to the optional 'prepend array or string size?' to write non-trivial structures to a binary file. I then read the file with the 'Read from Binary File' VI and everything is fine. I don't wire anything to the 'file (use dialog)' input (don't know if this can help).
However, after saving my VI for LabVIEW 7.1, I cannot read the binary files created with the LV7 version of the VI anymore. After examining the LV7 converted version of the VI, there is a 'FALSE' boolean constant that is wired to the equivalent of the 'prepend array or string size' input, which breaks the binary format that is expected.
The attached files are LV8 and 'saved for LV7' versions of a dummy VI that writes an array of 5 integers into a binary file. To test the bug, start LV8, open the LV8 version, run it and create a 'test-lv8.bin' file, then open the LV7 version, run it and create a 'test-lv7.bin' file. Check the content of the two files : the size of the array is indeed missing from the 'test-lv7.bin' file, which can be assimilated as a bug in my opinion.
I think I found another one too : if in LV8 I wire the 'cancelled' boolean output of the 'Open/Create/Replace file' to the selector of a case structure, the 'converted to LV7' version VI will have an error, saying the Case Structure selector is not wired.
Could someone please confirm these are indeed bugs ?
Thanks in advance and have a nice day.
Eric Batut
Attachments:
Test Binary File v7-v8 LV7.vi ‏15 KB
Test Binary File v7-v8 LV8.vi ‏7 KB

I'm using LV8.6 and need to read a .bin file created in MATLAB. This file obviously does not contain the 4 byte header that LabVIEW prepends .bin files with. So when I use Read from Binary File, I get no data (I'm trying to read an array of doubles). I've tried making my .bin file both in native and big-endian format and changing the representation (double, int64, float64) but none of this works. I noted that if I create the same array in a .bin file in LabVIEW and wire a FALSE to the "prepend array or string size?", my VI for reading .bin files can't read this file either.
Any work-arounds here?
(I'll try attaching my write & read VI's)
Attachments:
ReadWriteBinFile.zip ‏19 KB

Writing data from array to file

May i know how to write string from a array into a file.
I have use string tokenizer to extract every line from a file using readline and use stringtokenizer to spilt the line using tab delimiter for processing.
But if i want to write data from array to file with tab as a delimiter and how to go to the next line. How do i do that. Below is the task and i have state a simple example on a array i have and the file output that i want.
Pls advice.. Thanks
eg of a array
array[0] = Data
array[1] = One
array[2] = Data
array[3] = Two
array[4] = Final
array[5] = Data
From the above array, i want to write to a file so that it will appear something as below
Eg textfile.txt
Data One
Data Two
Final Data
PLs attached a simple code as a example as i am only begining to start useing the IO feature in java. Thanks

Really thanks for your help,
but u are mentioning that i have already know the number of countters in advance , that is to say the 2 * counters.
But is there a way to solve this problem which i mean if i dun know the number of predefined counters. Maybe i should say, there is more than 2 counters and in another situation, the counters will only be defined during runtime. Actually the solution u give will work nicely with 2 counters. but wat if the counter is more than 4, i wll have to concatenate the string a lot of time. so is there any solution around this problem. That why i am wandering if tere is any solution to write to the file when the counters can be only determined in runtime
Pls advice on the above with a code samples if possible.

Write to measurement file timing

I am trying to make a VI that allows the user to turn on and name channels through the front panel. After the user has configured the channels, they can push a button and record voltages from the enabled channels and save them using the "Write to Measurement File".vi. I would like the user to be able to record a measurement file that is consistent in length each time they push the button...in this case, 5 seconds of data. The current VI doesn't appear to be doing this...everytime I push the record button, the data gets recorded for 0.045 seconds. Apparently I must be missing something as this isn't behaving how I expected it to. See attached VI.
Attachments:
Select Channel rev 3.vi ‏244 KB

It waits 5 seconds then saves the last 10 samples. Because that is the way you programmed it. The while loop returns only the data from the last iteration.
Two ways to do what you want: 1. Read 5 seconds * 200 samples/second = 1000 samples. No loop required.
2. Read 10 samples at a time and accumulate the data until you have 5 seconds of data. To avoid memory reallocations the way to do this is to Initialize an array with 1000 elements outside the loop. Wire it to a shift register. Inside the loop Read the samples and use Replace Array Subset to put the new data into the initialized array. Wire the output of the shift register to the file VI.
You generally should not put any time consuming code inside an event structure. Read the caveats in the detailed help for the event structure. Consider a Producer/Consumer architecture.
Lynn

Write to binary file

I have a relatively large 3D array (Phase Settling), which I want to store in a Binary File. The array is a 15000 point sweep (after decimation), repeated up to 48 by 48 times (in two FOR loops, one inside the other), meaning it can end up having as many as 34,560,000 data points. At the moment, I am attempting to dump that 3D array into a Binary File in one go, using the following VI. There are two possile versions of this array (both the same size as each other) and, depending on which has just been tested, they will be written to their own individual file. Once both tests have been run and their results stored, the idea was to open both files, subtract one array from the other, and store the new 3D array to another Binary File whilst also displaying this latest data elsewhere in a higher-level VI.
After its first trial run, LabVIEW presents me with an error message saying something along the lines of "LabVIEW had run out of memory". I assume it would be to do with this VI, since that's where the first error code appeared (Error Code: 2), apparently originating in a 'Write to Binary File' function.
Any ideas as to how I could get round this first hurdle, or perhaps an alternative method I could try?
Thank you.
- James
Message Edited by James Mamakos on 04-08-2010 10:07 AM
Never say "Oops." Always say "Ah, interesting!"
Attachments:
Running out of LabVIEW memory when writing to binary file.PNG ‏30 KB

Well, as shown in the attached screen-shot, the error indicator shows an error code of 2, and that the error occurred in one of the Write to Binary File functions.
However, when trying to save this particular VI after a couple of tweaks, I was presented with the following pop-up alert message:
LabVIEW: Memory is full.
Cannot save VI "Compare Amp - calculate.vi".
LabVIEW Save error code 10: Default data space.
Anyway, returning back to the main problem at hand, I've though of a couple of possible solutions...
We don't really need a particularly high resolution to the data points for the comparison, so I could convert the array doubles into an array of singles to save space.
I should be able to implement the 'Write to Binary File' for the initial arrays into the outer FOR loop, thereby reducing the amount data written in each instance by a factor of up to 48. The only problem I can foresee in this is that I'm not sure how to append 2D arrays into a binary file such that, when the file is read, they would appear as (or be easily converted into) a 3D array.
As for the 'True' case in my case structure, am I being grossly inefficient in my passing of data from one place to the next? I know there are a lot of branches (and buffers?) of 3D arrays; is there a decent way to reduce this overhead by tweaking the data paths or something?
- James
P.S. The computer I'm using has 1GB RAM.
Message Edited by James Mamakos on 04-08-2010 12:39 PM
Never say "Oops." Always say "Ah, interesting!"
Attachments:
LabVIEW - error code 2.PNG ‏35 KB

Write to Text File - unflatten channel string

Hi all,
This is my first post on the forums! It's been very helpful for me but I have not been able to find a solution to my (simple) problem.
Operating system: Windows 7 (64-bit)
Labview 2012 Full Development
I'm using the DAQmx unflatten channel string to get the names of the channels, and when I Write to Text File, I get the names of channels to be displayed vertically, ie a new row for each channel in a column. I'd like to "transpose" this, but obviously you cannot transpose a 1d array. Any ideas on how I can do this?
Any and all ideas are appreciate, thank you in advance,
-AK
Solved!
Go to Solution.

Show us how you are doing this.
My guess is that once you get the data, you have linefeed characters separating the channel names rather than some other delimiter such as a comma or a tab.
Depedning on how you are going from the channel names to the file (a string, an array of strings, Write to Spreadsheet File, Write to Text file, ....) will determine the best way to fix the problem for you.

How to populate column titles for y values when using Write to Measurement File Express VI with a tab delimited text-based .lvm file?

The .lvm file generated by the Write to Measurement File Express VI includes column heading titles for the y values, but they are a default value of "untitled". See attached example of a sample file when opened in Excel, the values in question are highlighted. Is there a way to specify the column titles when the file is written?
This is a similar question to this posting, which received a work around response to use the Write to Spreadsheet File.vi, rather than a solution when using this VI.
Message Edited by Hightop Raven on 05-02-2007 03:37 PM
Attachments:
column_titles.gif ‏13 KB

Sorry for the late reply. I was out of the office Friday.
You can do it, but the code can get rather ugly. Under the hood, the dynamic data type (the dark blue wire) is an array of waveforms. In your case, the scalar values you convert to a dynamic data type are being converted to an array of waveforms, each waveform having one element. You have two options.
Explicitly convert your scalars to one-element waveforms (t0=0, dt=1) and add the title before conversion to a dynamic data type.
Convert your dynamic data type to an array of waveforms and loop through them to add the column labels. The conversion blocks are in the Signal Manipulation Express palette.
I would recommend 2, since it is the easiest to add. It is also the easiest to run only on the first iteration. Just put a case selector around the loop, wire the selection to the While loop iterator, and set the case containing the label code to 0. The default case simply passes through the dynamic data.
My apologies for not including a screen shot. I am in the process of upgrading my machine and can't run LabVIEW. If you need one, let me know and I can post one tomorrow.
This account is no longer active. Contact ShadesOfGray for current posts and information.

How to write data to file Java ME cldc 1.1 midp 2.0?

I newly in java me, please help me.
I make project in NetBeans 7.0.1. and use cldc 1.1 midp 2.0.
I want to write data to the file.
How can I do it?
I try to use FileOutputStream. But it don't exists in java.io
NetBeans shows me only this list of classes and interfaces in java.io:
ByteArrayInputStream, ByteArrayOutputStream, DataInput, DataInputStream, DataOutput, DataOutputStream, InputStream, InputStreamReader, OutputStream, OutputStreamWriter, PrintStream, Reader, Writer.
Why it so short?
And how I can write data to file?
Data can be array of bytes (byte[]) or Object it better.

You must use JSR 75: FileConnection. Please check the following article "Getting Started with the FileConnection APIs":
http://developers.sun.com/mobility/apis/articles/fileconnection/
Be sure to use FileSystemRegistry.listRoots().
And welcome to Java ME development. :)

Write arrays to file

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