I typed the example code from the "arpackpp.doc", and got a run time error like this:
here is my code:
and the matrix is
well, I answer my question...
element of irow, which is pointer to an array of row indices of the nonzero elements contained in nzval, should start from 0 not 1.
Related
The lowerbound of an array is always zero in VB.net, even if the first element is set to Nothing. So why do we need to use GetLowerBound(dimension) to get the index of the first element of an array in a particular dimension?
As per documentation found here:
https://learn.microsoft.com/en-us/dotnet/api/system.array.getlowerbound?view=net-6.0
There can be arrays that do not start with index 0:
Note that, although most arrays in .NET are zero-based (that is, the
GetLowerBound method returns zero for each dimension of an array),
.NET does support arrays that are not zero-based. Such arrays can be
created with the CreateInstance(Type, Int32[], Int32[]) method, and
can also be returned from unmanaged code.
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.
TLDR: I have 2 arrays indices = numpy.arange(9) and another that contains some of the numbers in indices (maybe none at all, maybe it'll contain [2,4,7]). The output I'd like for this example is [0,1,3,5,6,8]. What method can be used to achieve this?
Edit: I found a method which works somewhat: casting both arrays to a set then taking the difference of the two does give the correct result, but as a set, even if I pass this result to a numpy.array(). I'll update this if I find a solution for that.
Edit2: Casting the result of the subtraction to a list, then casting passing that to a numpy.array() resolved my issue.
I guess I posted this question a little prematurely, given that I found the solution for it myself, but maybe this'll be useful to somebody in future!
You can make use of boolean masking:-
indices[~numpy.isin(indices,[2,4,7])]
Explanation:-
we are using numpy.isin() method to find out the values exists or not in incides array and then using ~ so that this gives opposite result and finally we are passing this boolean mask to indices
With below code, I was expecting to swap two lists and was expecting all the elements from 'names' list to 'Excluded_list'using Pop() function. But it is not working expectedly, can someone please tell the issue with below code ??
names=['Ram','Sham','Mohan','John','Kuldeep']
Excluded_list=[]
print('names list',names)
print('Excluded list ',Excluded_list)
Code to swap/reprint lists
for name in names:
Excluded_list.append(names.pop())
print('names list',names)
print('Excluded list ',Excluded_list)
You are modifying "names" in the for-loop, which means that the "for name in names" does not evaluate as you expect.
Replace the for-loop with a while-loop.
while len(names):
Excluded_list.append(names.pop())
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