topic Re: How make array of string from different string in LabVIEW

How make array of string from different string

MaxiMuz1979 — Tue, 21 Feb 2017 14:19:33 GMT

Hi everyone !

I need get array of strings, which consist from defined (selected defined algorithms) strings. This string coming from "Pick Line" and I tried do this with help function "Insert Into Array Function " . But on the output I am getting the array with only 1 member.

Why did such occur ?

Re: How make array of string from different string

Norbert_B — Tue, 21 Feb 2017 14:29:47 GMT

Your VI needs improvement (quite some) in order to be readable.

Besides that, your issue has to do with a missing shift register for the string array.....

Re: How make array of string from different string

GerdW — Tue, 21 Feb 2017 14:32:27 GMT

Hi Muz,

Why did such occur ?

When you insert a string into an empty string array you get an array with just one element.

Seems reasonable to me…

Re: How make array of string from different string

MaxiMuz1979 — Tue, 21 Feb 2017 15:03:35 GMT

When you insert a string into an empty string array you get an array with just one element.

Seems reasonable to me…

I solved this problem. I can't get used to LabView. I must to looping the output functional block on the input through buffer.

Look like this.

Re: How make array of string from different string

RavensFan — Tue, 21 Feb 2017 15:07:37 GMT

If you are always putting the new element at either the beginning or end of an array, then you should just use Build Array. Insert into Array should only be used when you might be "inserting" new elements in the middle of an array.

Re: How make array of string from different string

GerdW — Tue, 21 Feb 2017 15:11:00 GMT

And you should (most probably) also initialize your shift register…

Re: How make array of string from different string

Norbert_B — Tue, 21 Feb 2017 15:13:51 GMT

Your VI still requires a lot of rework to be in proper shape. There are couple of code segments which can create severe issues on the long term:

a) Uninitialized shift register will keep the data from the last VI execution (as long as the VI stays in memory!). That means that your string array keeps growing with repetitive VI calls until you unload the VI (most likely shut down LV) or your systems runs out of memory

b) A for loop already has a method of limiting the number of iterations. Your conditional terminal makes no sense if the VI connected to N already passes '4'

c) Add function is Rube-Goldberg. Please get rid of it

d) 'sub-optimal' wire routing leads to difficult readable code. If more code is added, this adds up to a real pain

Re: How make array of string from different string

proland1121 — Tue, 21 Feb 2017 16:10:20 GMT

One of the biggest hurdles that non-LabVIEW people face when starting is dealing with dataflow instead of variables. In other languages, you would declare an array with the desired number of elements, then populate them sequentially within the for loop. Here, "Out Array" is not a variable which is appended at each iteration of the loop, but an indicator on the front panel which is "re-assigned" at each iteration of your loop.

If you do not need "Out Array" updated at each iteration of the loop, you could use an auto-indexing output tunnel (instead of the shift register) and place "out array" outside the for loop.

Re: How make array of string from different string

crossrulz — Tue, 21 Feb 2017 17:52:30 GMT

My first thought is "where is the data used to pick line?" If that is a giant string that comes in before the loop, you could just use Spreadsheet String To Array to turn the giant string into an array of strings (an element for each line) and then use an Auto-indexing Tunnel to loop through the lines. It would greatly simplify your code (no need to wire the N or use the conditional terminal, eliminate the Pick Line and the need to build the array inside of the loop, etc.)

Re: How make array of string from different string

MaxiMuz1979 — Wed, 22 Feb 2017 07:26:29 GMT

a) Uninitialized shift register will keep the data from the last VI execution (as long as the VI stays in memory!).

I agree with it.

That means that your string array keeps growing with repetitive VI calls until you unload the VI (most likely shut down LV) or your systems runs out of memory

How can the array string keeps growing if every time at the begin it has null length ?

b) A for loop already has a method of limiting the number of iterations. Your conditional terminal makes no sense if the VI connected to N already passes '4'

- I know! It will be changing

c) Add function is Rube-Goldberg. Please get rid of it

Do you mean the method of creating array ?

Re: How make array of string from different string

Norbert_B — Wed, 22 Feb 2017 08:07:02 GMT

@MaxiMuz1979 wrote:

[...]

That means that your string array keeps growing with repetitive VI calls until you unload the VI (most likely shut down LV) or your systems runs out of memory

How can the array string keeps growing if every time at the begin it has null length ?

[...]

The array in the shift register has a length of 0 only before the first call. Once the VI finished running the first time, the array in the shift register has a length of four elements. This array is NOT RESET to a length of zero elements because you DO NOT RE-INIT the shift register with an empty array.

Furthermore, you use "Insert into array" and use the iterator to insert elements. That means for the second run of the VI:

- The shift register contains a string array with four elements

- You start to PREPEND new elements

That means, runtime performance sucks and you have a "memory leak- like" behavior of growing memory consumption. However, it is not a leak, it is what you tell LV to do!

@MaxiMuz1979 wrote:

[...]

c) Add function is Rube-Goldberg. Please get rid of it

Do you mean the method of creating array ?

No, i mean the "Add" function (the yellowish triangle with '+' inside). It serves no purpose as you add 0 to the iterator. So it is a complete waste of block diagram space. Depending on the LV version, it is possible that the compiler removes that unnecessary code, but it could also bloat the execution code of the VI. Please remove it (with the constant '0').

Re: How make array of string from different string

MaxiMuz1979 — Wed, 22 Feb 2017 08:08:20 GMT

@crossrulz wrote:

My first thought is "where is the data used to pick line?" If that is a giant string that comes in before the loop, you could just use Spreadsheet String To Array to turn the giant string into an array of strings (an element for each line) and then use an Auto-indexing Tunnel to loop through the lines.

I need to use array of strings in the loop.

Re: How make array of string from different string

MaxiMuz1979 — Wed, 22 Feb 2017 10:53:52 GMT

@Norbert_B wrote:

@MaxiMuz1979 wrote:

Furthermore, you use "Insert into array" and use the iterator to insert elements. That means for the second run of the VI:

- The shift register contains a string array with four elements

really is the shift register contain all array ? I think, the shift register can contains only one member such as one string. Isn't it ?

Re: How make array of string from different string

Norbert_B — Wed, 22 Feb 2017 11:54:26 GMT

You have a single 1D array of strings in the shift register. So yes, the following is true as you state:

- There array has only elements of one specific data type (fundamental property of arrays in all programming languages)

- The array has only one dimension

However, that does not define/restrict how many elements are in the array. In your code, the array is not reinitialized to be empty for consecutive VI executions. That means that each call to VI adds new elements!

Re: How make array of string from different string

GerdW — Wed, 22 Feb 2017 11:56:35 GMT

Hi Muz,

I think, the shift register can contains only one member such as one string. Isn't it ?

It isn't! A shift register can take any datatype you like…

I think you should take the free beginner courses offered by NI!

And I suggest you create some simple VIs to "play around" and "try on your own": such things really help to understand how certain parts of LabVIEW work…

Re: How make array of string from different string

MaxiMuz1979 — Wed, 22 Feb 2017 13:21:55 GMT

@GerdW wrote:

I think you should take the free beginner courses offered by NI!

And I suggest you create some simple VIs to "play around" and "try on your own": such things really help to understand how certain parts of LabVIEW work…

What course do you mean ?

Re: How make array of string from different string

GerdW — Wed, 22 Feb 2017 13:42:13 GMT

Hi Muz,

did you notice the header on top of the LabVIEW forum?

It says "Getting started…"

Re: How make array of string from different string

MaxiMuz1979 — Mon, 27 Feb 2017 09:13:40 GMT

Yes, I saw