I want to format my command usage with docopt.
I found out that
<parameter>...
means that you can write a parameter multiple time.
My problem is, that I have an argument that you can repeat multiple times but it has a limit. I don't want to write
<parameter> [<parameter> <parameter> <parameter> <parameter> <parameter> <parameter>]
with the correct count of the
<parameter>
tag. Is there a shorter way to specify that you can use the parameter mutliple times but the maximum is 15 times?
Short answer: No, you can't specify a maximum number of occurrences of a pattern in docopt. You can only specify a minimum. You will have to deal with that afterwards (or write X time).
Related
I am writing a Testbench using Systemverilog and I want to have the freedom to choose in each test to either randomize some variables or specify their value (from a .do file or from command line). Is there any option in Systemverilog to do this?
There are many things you can do, but the simplest is putting +some_variable=value on the command line, and then in your code
if (!$value$plusargs("some_variable=%0d",some_variable)
some_variable = $urandom;
Declare a variable and use $urandom or $urandom_range to generate random values. When you want to pass values from the command line, you can use $value$plusargs.
Read up on Chapter 21 (Input/output system tasks) of the LRM to find examples.
I am doing binary classification using vowpal-wabbit. A particular record(set of features) has 10 zeroes and 5 ones. So, I am creating two lines in vowpal-format
-1 10 `50 |f f1
1 5 `50 |f f1
Since the prediction(probability) for both these records would be same, I want to keep the same tag, so that I can dedupe the predictions({tag,prediction}) later and join with my original raw-data.
Is it possible to keep the same tag for more than one record in vowpal-wabbit?
First, the syntax above isn't correct
To be identified as such, tags should either:
Touch the | separator (no space between them) OR
The leading quote, needs to be a simple quote, not a backquote, by convention.
(or both).
Otherwise you get:
warning: `50 is not a good float, replacing with 0
warning: `50 is not a good float, replacing with 0
Which hints that vw interprets these "tags" as prediction-base.
For details, see Input format in the official documentation
Once the example is fixed to the correct syntax:
-1 10 '50|f f1
1 5 '50|f f1
Which runs fine, we can answer the question:
Is it possible to keep the same tag for more than one record in vowpal-wabbit?
Yes, you can. The tag is merely a simple way to connect input and output (when predictions are involved), there's no check for uniqueness anywhere. If you duplicate tags on input, you'll simply get the same duplicate tags on prediction output as well.
More notes:
Even if two examples are identical, you may get different predictions, if the model has changed somewhat in between them. Remember vw is an online learner, so the model can continuously change with each example unless you add the -t (test-only, don't learn) option.
Features whose value is zero are ignored, so you can drop them. The standard way in vw to say this is 'positive' and this is 'negative' is to use the values {+1, -1}. This is true for both labels and input features.
I know that there are hash functions that from a variable length input can give a fixed output. To take the simplest one, using the module of ten no matter how big is the input number I will always get an output between 0 and 9.
I need to do have from an unknown password, a variable length output. My first thought was to use the module, increasing the prim number as much as many digits I need to have as output.
My problems are:
I must handle short passwords as well as I would with long passwords;
I don't know how long should the output be before writing the program, and even though I would know after the user has set the password I may need to change it if he modifies the file.
My first thought was using a simple function and modify it based on my needs.
If I have to hash 123 but I need to have 5 characters as output, that's what I would do:
I add 2 zeros on the right, changing the input to 12300;
I take the lowest 5 digits prime number (10007);
And I then I have my hash doing 12300 % 10007 = 02293.
But since I would probably need output in the order of hundreds if not thousands I'm pretty sure module is not the solution to my problem.
I could also try to create my own hash function, but I have no idea how to verify if it works or if it's trash.
Are there some common solutions in literature for this kind of problem?
I am defining a variable in the beginning of my source code in MATLAB. Now I would like to know at which lines this variable effects something. In other words, I would like to see all lines in which that variable is read out. This wish does not only include all accesses in the current function, but also possible accesses in sub-functions that use this variable as an input argument. In this way, I can see in a quick way where my change of this variable takes any influence.
Is there any possibility to do so in MATLAB? A graphical marking of the corresponding lines would be nice but a command line output might be even more practical.
You may always use "Find Files" to search for a certain keyword or expression. In my R2012a/Windows version is in Edit > Find Files..., with the keyboard shortcut [CTRL] + [SHIFT] + [F].
The result will be a list of lines where the searched string is found, in all the files found in the specified folder. Please check out the options in the search dialog for more details and flexibility.
Later edit: thanks to #zinjaai, I noticed that #tc88 required that this tool should track the effect of the name of the variable inside the functions/subfunctions. I think this is:
very difficult to achieve. The problem of running trough all the possible values and branching on every possible conditional expression is... well is hard. I think is halting-problem-hard.
in 90% of the case the assumption that the output of a function is influenced by the input is true. But the input and the output are part of the same statement (assigning the result of a function) so looking for where the variable is used as argument should suffice to identify what output variables are affected..
There are perverse cases where functions will alter arguments that are handle-type (because the argument is not copied, but referenced). This side-effect will break the assumption 2, and is one of the main reasons why 1. Outlining the cases when these side effects take place is again, hard, and is better to assume that all of them are modified.
Some other cases are inherently undecidable, because they don't depend on the computer states, but on the state of the "outside world". Example: suppose one calls uigetfile. The function returns a char type when the user selects a file, and a double type for the case when the user chooses not to select a file. Obviously the two cases will be treated differently. How could you know which variables are created/modified before the user deciding?
In conclusion: I think that human intuition, plus the MATLAB Debugger (for run time), and the Find Files (for quick search where a variable is used) and depfun (for quick identification of function dependence) is way cheaper. But I would like to be wrong. :-)
I am using PCRE|^/foo/(.*?)(?::(?:bar)?)?$| or |^/foo/(.*?)(?::bar)?:?$| this will be a replace so we want to strip : and :bar from the end while doing the replacement. I know the two are not exactly the same but it does not matter much here.
I would use the first one as it only has to check for : once. The second one could match the first three characters of :bat before having to backtrack, then check for : again. Also, the second one could match :bar: whereas the first one can't. The actual speed difference would be tiny. The second way would be better written as /^\/foo\/(.*?)(?::bar|:)?$/
Try not to use regex metacharacters as delimiters!