I'm trying to clear an array after each iteration of a for loop in LabVIEW, but the way I've implemented it has the values not going directly to what I want, but it changes with previous values in other parts of the array.
It isn't shown, but this code is inside of a for-loop that iterates through another numeric array.
I know that if I get the array to clear properly after each loop iteration, this should work. How do I do that? I'm a beginner at Labview but have been coding for awhile - help is appreciated!!!
[![labview add to array][2]][2]
It looks as if you're not quite used to how LabVIEW passes data around yet. There's no need to use lots of value property nodes for the same control or indicator within one structure; if you want to use the same data in more than one place, just branch the wire. Perhaps you're thinking that a LabVIEW control or indicator is equivalent to a variable in text languages, and you need to use a property node to get or set it. Instead, think of the wire as the variable. If you want to pass the output of one operation to the input of another, just wire the output to the input.
The indicators with terminals inside your loop will be updated with new values every loop iteration, and the code inside the loop should execute faster than a human can read those values, so once the loop has finished all the outputs except the final values will be lost. Is that what you intended, or do you want to accumulate or store them in some way?
I can see that in each loop iteration you're reading two values from a config file, and the section is specified by the string value of one element of the numeric array Array. You're displaying the two values in the indicators PICKERING and SUBUNIT. If you can describe in words (or pseudocode, or a text language you're used to) what manipulation of data you're actually trying to do in the rest of this code, we may be able to make more specific suggestions.
First of all, I'm assuming that the desired order of operations is the following:
Putting the value of Pickering into Array 2
Extracting from Array 2 the values to put in Pickering 1 and Pickering 2
Putting Array 2 back to its original value
If this is the case, with your current code you can't be sure that operation 1 will be executed be fore operation 2. In fact, the order of these operations can't be pre-determined. You must force the dataflow, for example by creating a sequence structure. You will put the code related to 1 in the first frame, then code related to operation 2 in the second.
Then, to put Array 2 back to it's original value I would add a third frame, where you force an empty array into the Value property node of Array 2 (the tool you use for pickering, but as input and not as output).
The sequence structure has to be inside the for loop.
I have never used the property node Reinit to default, so I can't help you with that.
Unfortunately I can't run Labview on this PC but I hope my explanation was clear enough, if not tell me and I will try to be more specific.
Related
I'm planning to overwrite a Field value using pandas but that does not seem to work. Am i missing anything as part of the code below?
`for row_no in range(df.shape[0]):
rowIndex = df.index[row_no]
if re.search('Fex|Process|PIP|VIP|Generic|Mobility', df.loc[rowIndex].VPC_Sub_Cat, re.I):
print(df.loc[rowIndex].Headline)
print(df.loc[rowIndex].VPC_Sub_Cat)
print(df.loc[rowIndex].Final_Result)
df.loc[rowIndex].Final_Result = 0
print(df.loc[rowIndex].Final_Result)
break`
The output that I get after running this piece of code is:
This is the description of the issue...
VPC-Generic
1
1
Also can i achieve the same thing using a function and applying that on a data frame? kindly let me know.
df.loc[rowIndex].Final_Result is equals to (in most situation though...)
df.loc[rowIndex]['Final_Result']
This will cause a chained assignment (see here #Warning)
Whether a copy or a reference is returned for a setting operation, may depend on the context. This is sometimes called chained assignment and should be avoided. See Returning a View versus Copy.
And then from Returning a view versus a copy
But it turns out that assigning to the product of chained indexing has inherently unpredictable results.
So using df.loc[rowIndex, 'Final_Result'] to make sure that the value you assigned is view, not copy.
I'm in the middle of transferring some VB code to another language, but I don't understand what's supposed to be happening here.
Dim foo(7,0) as Date
Then later in the code I get something like foo(5,3) and I believe the output to be a Date object. There is no function written to describe foo so I'm assuming it's a multi-dimensional array. But cast as a Date? I'm confused, please help.
I don't know what's going on their either, because this:
Dim foo(7,0) as Date
declares a two dimensional array that is effectively a one dimensional array because the second dimension has an upper bound of 0...
... and then you claim that the second dimension is later indexed with 3, which is outside the bounds. foo(5, 0) would be fine, but the sixth row (if you want to think of the 5 that way) has 1 column, so retrieving the fourth is an IndexOutOfRangeException. Presumably this has been ReDim'd at some point between then and now
To have the debugger help you out, run the code, stop on it and point to foo or look in the LOCALS window:
Bounded in red is the variable analyzer as a tooltip and in the locals. It shows Date to be a 2D array. It also helpfully lists all the contents. Bounded in blue is the error you get if you try and access index 3 of an array that stops at index 0
Make that 2D array actually have an appreciable width:
And you can see it's just a block of Date
Enterprise Architect 13.5.
I made MDG technology extending Object metatype. I have a shape script for my stereotype working well. I need to print several predefined run-state parameters for element. Is it possible to access to run-state params within Shape ?
As Geert already commented there is no direct way to get the runstate variables from an object. You might send a feature request to Sparx. But I'm pretty sure you can't hold your breath long enough to see it in time (if at all).
So if you really need the runstate in the script the only way is to use an add-in. It's actually not too difficult to create one and Geert has a nice intro how to create it in 10 minutes. In your shape script you can print a string restult returned from an operation like
print("#addin:myAddIn,pFunc1#")
where myAddIn is the name of the registered operation and pFunc1 is a parameter you pass to it. In order to control the script flow you can use
hasproperty('addin:myAddIn,pFunc2','1')
which evaluates the returned string to match or not match the string 1.
I once got that to work with no too much hassle. But until now I never had the real need to use it somewhere in production. Know that the addin is called from the interpreted script for each shaped element on the diagram and might (dramatically) affect rendering times.
I would like to know what is preferred...
Dim sLines() As String = s.Split(NewLine)
For each:
For Each sLines_item As String In sLines
.GetUpperBound:
For i As Integer = 0 To sLines.GetUpperBound(0)
I have no idea why the "For Each" was introduced for such cases. Until now I have only used .GetUpperBound, and I don't see any PRO for the "For Each".
Thank you
ps: When I use ."GetUpperBound(0)", I do know that I am iterating over the vector.
The "For Each" in contrast sounds like "I don't care in which order the vector is given to me". But that is just personal gusto, I guess.
Short answer: Do not use GetUpperBound(). The only advantage of GetUpperBound() is that it works for multi-dimensional arrays, where Length doesn't work. However, even that usage is outdated since there is Array.GetLength() available that takes the dimension parameter. For all other uses, For i = 0 to Array.Length - 1 is better and probably the fastest option.
It's largely a personal preference.
If you need to alter the elements of the array, you should use For i ... because changing sLines_item will not affect the corresponding array element.
If you need to delete elements of the array, you can iterate For i = ubound(sLines) to 0 step -1 (or the equivalent).
Short answer
You should always use For Each on IEnumerable types unless you have no other choice.
Long answer
Contrary to the popular understanding, For Each is not a syntactic sugar on top of For Next. It will not necessarily iterate over every element of its source. It is a syntactic sugar on top of IEnumerable.GetEnumerator(). For Each will first get an enumerator to its source then loop until it cannot enumerate further. Basically, it will be replaced by the following code. Keep in mind that this is an oversimplification.
' Ask the source for a way to enumerate its content in a forward only manner.
Dim enumerator As IEnumerator = sLines.GetEnumerator()
' Loop until there is no more element in front of us.
While enumerator.Next() Then
' Invoke back the content of the for each block by passing
' the currently enumerated element.
forEachContent.Invoke(enumerator.Current)
End While
The major difference between this and a classical For Next loop is that it does not depend on any length. This fixes two limitations in modern .NET languages. The first one has to do with the Count method. IEnumerable provides a Count method, but the implementation might not be able to keep track of the actual amount of elements it stores. Because of this, calling IEnumerable.Count might cause the source to be iterated over to actually count the amount of element it contains. Moreover, doing this as the end value for traditional For Next loop will cause this process to be done for every element in the loop. This is very slow. Here is an illustration of this process:
For i As Integer = 0 To source.Count() ' This here will cause Count to be
' evaluated for every element in source.
DoSomething(source(i))
Next
The use of For Each fixes this by never requesting the length of the source.
The second limitation it fixes is the lack of a concept for arrays with infinite amount of elements. An example of such cases would be an array containing every digit of PI where each digit is only calculated when you request them. This is where LINQ makes its entrance and really shines because it enables you to write the following code:
Dim piWith10DigitPrecision = From d In InfinitePiSource
Take 10
Dim piWith250DigitPrecision = From d In InfinitePiSource
Take 250
Dim infite2PiSource = From d In InfinitePiSource
Select d * 2
Now, in an infinite source, you cannot depend on a length to iterate over all of its elements. It has an infinite length thus making a traditional For Next loop an infinite loop. This does not change anything for the first two examples I have given with pi because we explicitly provides the amount of elements we want, but it does for the third one. When would you stop iterating? For Each, when combined with Yield (used by the Take operator), makes sure that you never iterate until you actually requests a specific value.
You might have already figured it out by now but these two things means that For Each effectively have no concept of bounds because it simply does not require them. The only use for GetLowerBound and GetUpperBound are for non-zero-indexed arrays. For instance, you might have an array that indexes values from 1 instead of zero. Even then, you only need GetLowerBound and Length. Obviously, this is only if the position of the element in the source actually matters. If it does not, you can still use For Each to iterate over all elements as it is bound agnostic.
Also, as already mentioned, GetLength should be used for zero-indexed multi-dimensional arrays, again, only if the position of the element matters and not just the element itself.
I have a complex iterative spreadsheet in which I want to use a UDF to calculate the heat transfer coefficient of a heat exchanger. The function has 5 arguments (2 strings and 3 doubles). The strings and 1 double pass just fine. The remaining two don't seem to go through at all. A watch on problematic arguments shows them to be equal to zero. I tried redefining the arguments as variants, and then I can find the value I want in the "value2" field. However, as soon as I try to access it (via varName.Value2) it disappears (the watch suddenly lists the field as "Empty").
The cells passed into the function for the problematic arguments are heavily dependent on the rest of the spreadsheet, and their value changes almost every iteration.
Has anyone seen this before and know of a workaround?
I use UDFs with +6 input variables (the standard types as well as variants), and I have noticed (this is my interpreation of what happens) that sometimes the excel calc engine tries to trigger the UDF before all the input values become calced and available. From the debug view this is seen as the function making "false starts" and stopping to execute mid-procedure (thread is lost) so debugging-wise it shows a strange behaviour.
However, when written into a cell the function still calculates and returns correctly.