scalar

问题 I have been trying to achieve something which should pretty trivial and is trivial in Matlab . I want to simply achieve something such as: cv::Mat sample = [4 5 6; 4 2 5; 1 4 2]; sample = 5*sample; After which sample should just be: [20 24 30; 20 10 25; 5 20 10] I have tried scaleAdd , Mul , Multiply and neither allow a scalar multiplier and require a matrix of the same "size and type". In this scenario I could create a Matrix of Ones and then use the scale parameter but that seems so very

问题 Property 'Latitude' is a scalar type on class 'LatitudeLongitude'. Cannot generate a setter method for it. When I generated codes for my managed object, I got a message whether I want scalar properties for primitive data type. should I use it? I want to make this application compatible with iPhone 3 - 5 is there any issues with this problem? 回答1: When you use scalar properties you have to provide implementations of getters and setters for those properties by yourself, as described in

问题 I have a data in the following format. x y density . . . . . . . . . Here, density is the scalar. How to perform gradient on this dataset? I tried the gradient operator in Matlab. However, it returns only a scalar. Note: Both x and y are uniformly spaced with unit spacing. The boundary points end as floating point numbers, as it is clipped data. 回答1: You can sort the rows of your data so that the data points can be reshaped into a 2D matrix. You can then compute the gradient of that . % Sort

问题 In Robot Framework, we can assign a list to a Scalar Variable or to a List Variable, as shown below: | @{list} = | Create List | a | b | c | | ${scalar} = | Create List | a | b | c | What is the difference between a List Variable and a Scalar Variable containing a list? 回答1: In case of the assignment shown in your question, there is no difference. If you log each of those you'll get the exact same output. Note : this functionality was introduced in version 2.8 (see Using scalar variables as

问题 I am doing the following, but it is not working properly: my $enabled = $hash && $hash->{'key'} && $hash->{'key'}->{'enabled'} && $hash->{'key'}->{'active'}; Is this an acceptable way to assign a boolean value to a scalar variable? My code is misbehaving in strange ways, as it is, and I believe it is because of this assignment. I have validated that the individual values exist for all of these keys and are set to a value. P.S. Sorry for being a noob! I googled for ~10 minutes and couldn't

问题 The following example is taken from the Strings and Characters documentation: The values 55357 ( U+D83D in hex) and 56374 ( U+DC36 in hex) are the surrogate pairs that form the Unicode scalar U+1F436 , which is the DOG FACE character. Is there any way to go the other direction? That is, can I convert a surrogate pair into a scalar? I tried let myChar: Character = "\u{D83D}\u{DC36}" but I got an "Invalid Unicode scalar" error. This Objective C answer and this project seem to be custom

问题 This may be a simple question, but I can not figure out how to do this. Lets say that I have two variables as follows. a = 2 b = 3 I want to construct a DataFrame from this: df2 = pd.DataFrame({'A':a,'B':b}) This generates an error: ValueError: If using all scalar values, you must pass an index I tried this also: df2 = (pd.DataFrame({'a':a,'b':b})).reset_index() This gives the same error message. 回答1: The error message says that if you're passing scalar values, you have to pass an index. So

问题 I am doing some quick calculations on a scalar value from a numpy array. As it says in the documentation, The primary advantage of using array scalars is that they preserve the array type (Python may not have a matching scalar type available, e.g. int16)... But is there a better (faster, and more concise) way of assigning a new value to an existing array scalar than this: >>> x = np.array(2.0, dtype='float32') which works but is not that convenient (I am doing other arithmetic and want to

问题 I am reading a file into a SCALAR by using: open FILE, "<", $filename or error_out("Error opening $filename"); read FILE, my $buffer, -s $filename; close FILE; I am not sure how to think of the "new" $buffer / SCALAR type. Is it a string? An array? How to go through it line-by-line? 回答1: First, I recommend you use the following to read the file: my $buffer = do { open(my $fh, '<', $filename) or error_out("Error opening $filename: $!"); local $/; <$fh> }; Note the removal of the useless and

问题 Looking into the Const::Fast source I noticed that it used the built-in function Internals::SvREADONLY internally. Is it safe to use that function directly in my Perl script? It seems to be present in core from Perl 5.8. my $PI = 4 * atan2 1, 1; Internals::SvREADONLY($PI => 1); $PI = 2.718; # Modification of a read-only value attempted at .. 回答1: C:\>perldoc Internals No documentation found for "Internals". No. More specifically, the package is named "Internals" for a reason. It is not