If one looks at the (e.g.) ggplot2::scale_y_continuous, the default value of many of the arguments is set to waiver(), e.g. for breaks:
‘waiver()’ for the default breaks computed by the
transformation object
How does one figure out/look at how these defaults are computed? Let's say I want to find the breaks for scale_y_log10(). ?scales::log10_trans doesn't say anything about computation of breakpoints.
I think log10_trans()$breaks might do it, which is the same as ?log_breaks. Not sure how to figure this out in general, though ...
Related
It has been a while I am confused between these and I would like to see if there is a way to easily distinguish between these in a practical and fast way.
assuming df is a pandas data frame object, please see below:
while using pandas, this is what I noticed. To access/perform some methods, you have to use pd.method(df,*args) sometimes. To access some other ones, you need to use df.method(*args). Interestingly, there are some methods that work either way ...
Let's clarify this a bit more with some examples: while it totally makes sense to me to use pd.read_csv (), not df.read_csv, since there is no df created yet, I have a hard time making sense of the following examples:
1- correct: pd.getdummies(df,*args) --- incorrect: df.getdummies(*args)
2- correct: df.groupby(*args) --- incorrect: pd.groupby(df,*args)
3- correct: df.isnull() AND pd.isnull(df)
I am pretty sure you can also come up with many other examples as above. I personally find this challenging to keep in mind which one is which and found myself wasting a lot of time in total code development/analysis cycle trying to guessing if I should use pd.method (df) or df.method() for different things.
My main question is: how do you guys handle this? did you also find this issue challenging? is there any way to quickly understand which one to use ? am I missing something here?
Thanks
I am trying to solve a nonlinear program with Direct collocation in drake. I want to regain the solution when SNOPT solved the program successfully. First I saved the initial guess of each variable in a .txt file, then I read the initial guess and set decision variables by SetInitialGuess() , and change nothing else, but I did not get the same solution, WHY?
MOREOVER, when I run more times, the latter solutions are same.
e.g.
solution1 != solution2; solution2 == solution3; solution3 == solution4;.....
I have check each initial guess to make sure they are same. Is there options in SNOPT or initial settings in NP should be set beside the initial guess of decision variables to get a same solution?
Without knowing more about your program, one possible reason is that when you save the initial guess to a.txt, the floating number get truncated when print it to a txt file. So in the second run, the initial guess is not exactly the same as the first run. And this tiny difference in the initial guess causes the SNOPT to find a different solution. For solution 2, 3, 4, do they all load the initial guess from a.txt?
In order to print the floating number to the txt file, you could use setprecision command.
This might be an odd question, but I'm looking for a word to use in a function name. I'm normally good at coming up with succinct, meaningful function names, but this one has me stumped so I thought I'd appeal for help.
The function will take some desired state as an argument and compare it to the current state. If no change is needed, the function will exit normally without doing anything. Otherwise, the function will take some action to achieve the desired state.
For example, if wanted to make sure the front door was closed, i might say:
my_house.<something>_front_door('closed')
What word or term should use in place of the something? I'd like it to be short, readable, and minimize the astonishment factor.
A couple clarifying points...
I would want someone calling the function to intuitively know they didn't need to wrap the function an 'if' that checks the current state. For example, this would be bad:
if my_house.front_door_is_open():
my_house.<something>_front_door('closed')
Also, they should know that the function won't throw an exception if the desired state matches the current state. So this should never happen:
try:
my_house.<something>_front_door('closed')
except DoorWasAlreadyClosedException:
pass
Here are some options I've considered:
my_house.set_front_door('closed')
my_house.setne_front_door('closed') # ne=not equal, from the setne x86 instruction
my_house.ensure_front_door('closed')
my_house.configure_front_door('closed')
my_house.update_front_door('closed')
my_house.make_front_door('closed')
my_house.remediate_front_door('closed')
And I'm open to other forms, but most I've thought of don't improve readability. Such as...
my_house.ensure_front_door_is('closed')
my_house.conditionally_update_front_door('closed')
my_house.change_front_door_if_needed('closed')
Thanks for any input!
I would use "ensure" as its succinct, descriptive and to the point:
EnsureCustomerExists(CustomerID)
EnsureDoorState(DoorStates.Closed)
EnsureUserInterface(GUIStates.Disabled)
Interesting question!
From the info that you have supplied, it seems to me that setstate (or simply set, if you are setting other things than states) would be fine, though ensure is good if you want to really emphasize the redundancy of an if.
To me it is however perfectly intuitive that setting a state does not throw an exception, or require an if. Think of setting the state of any other variable:
In C:
int i;
i = 5; // Would you expect this to throw an exception if i was already 5?
// Would you write
if (i != 5)
i = 5;
// ?
Also it only takes about one sentence to document this behaviour:
The function does nothing if the
current state equals the requested
state.
EDIT: Actually, thinking about it, if it is really important to you (for some reason) that the user is not confused about this, I would in fact pick ensure (or some other non-standard name). Why? Because as a user, a name like that would make me scratch my head a bit and look up the documentation ("This is more than just an ordinary set-function, apparently").
EDIT 2: Only you know how you design your programs, and which function name fits in best. From what you are saying, it seems like your setting functions sometimes throw exceptions, and you need to name a setting function that doesn't - e.g. set_missile_target. If that is the case, I think you should consider the set_if, set_when, set_cond or cond_set names. Which one would kind of depend on the rest of your code. I would also add that one line of documentation (or two, if you're generous), which clarifies the whole thing.
For example:
// Sets missile target if current target is not already the requested target,
// in which case it does nothing. No exceptions are thrown.
function cond_set_missile_target ()
or function cond_set_MissileTarget ()
or function condSet_MissileTarget ()
or function condSetMissileTarget ()
ensure is not so bad, but to me it implies only that there is additional logic required to set the state (e.g. multiple states tied together, or other complications). It helps to make the user avoid adding unnecessary ifs, but it does not help much with the exception issue. I would expect an ensure function to throw an exception sooner than a set function, since the ensure function clearly has more responsibilities for, well, ensuring that this setting operation is in fact done right.
I'd go for ensure for the function you describe. I'd also use camelCase, but I suppose you may be in a language that prefers underscores.
You could always document (shock!) your API so that others don't make the mistakes you describe.
In LaTeX, how can I define a string variable whose content is used instead of the variable in the compiled PDF?
Let's say I'm writing a tech doc on a software and I want to define the package name in the preamble or somewhere so that if its name changes, I don't have to replace it in a lot of places but only in one place.
add the following to you preamble:
\newcommand{\newCommandName}{text to insert}
Then you can just use \newCommandName{} in the text
For more info on \newcommand, see e.g. wikibooks
Example:
\documentclass{article}
\newcommand\x{30}
\begin{document}
\x
\end{document}
Output:
30
Use \def command:
\def \variable {Something that's better to use as a variable}
Be aware that \def overrides preexisting macros without any warnings and therefore can cause various subtle errors. To overcome this either use namespaced variables like my_var or fall back to \newcommand, \renewcommand commands instead.
For variables describing distances, you would use \newlength (and manipulate the values with \setlength, \addlength, \settoheight, \settolength and \settodepth).
Similarly you have access to \newcounter for things like section and figure numbers which should increment throughout the document. I've used this one in the past to provide code samples that were numbered separatly of other figures...
Also of note is \makebox which allows you to store a bit of laid-out document for later re-use (and for use with \settolength...).
If you want to use \newcommand, you can also include \usepackage{xspace} and define command by \newcommand{\newCommandName}{text to insert\xspace}.
This can allow you to just use \newCommandName rather than \newCommandName{}.
For more detail, http://www.math.tamu.edu/~harold.boas/courses/math696/why-macros.html
I think you probably want to use a token list for this purpose:
to set up the token list
\newtoks\packagename
to assign the name:
\packagename={New Name for the package}
to put the name into your output:
\the\packagename.
In algebra if I make the statement x + y = 3, the variables I used will hold the values either 2 and 1 or 1 and 2. I know that assignment in programming is not the same thing, but I got to wondering. If I wanted to represent the value of, say, a quantumly weird particle, I would want my variable to have two values at the same time and to have it resolve into one or the other later. Or maybe I'm just dreaming?
Is it possible to say something like i = 3 or 2;?
This is one of the features planned for Perl 6 (junctions), with syntax that should look like my $a = 1|2|3;
If ever implemented, it would work intuitively, like $a==1 being true at the same time as $a==2. Also, for example, $a+1 would give you a value of 2|3|4.
This feature is actually available in Perl5 as well through Perl6::Junction and Quantum::Superpositions modules, but without the syntax sugar (through 'functions' all and any).
At least for comparison (b < any(1,2,3)) it was also available in Microsoft Cω experimental language, however it was not documented anywhere (I just tried it when I was looking at Cω and it just worked).
You can't do this with native types, but there's nothing stopping you from creating a variable object (presuming you are using an OO language) which has a range of values or even a probability density function rather than an actual value.
You will also need to define all the mathematical operators between your variables and your variables and native scalars. Same goes for the equality and assignment operators.
numpy arrays do something similar for vectors and matrices.
That's also the kind of thing you can do in Prolog. You define rules that constraint your variables and then let Prolog resolve them ...
It takes some time to get used to it, but it is wonderful for certain problems once you know how to use it ...
Damien Conways Quantum::Superpositions might do what you want,
https://metacpan.org/pod/Quantum::Superpositions
You might need your crack-pipe however.
What you're asking seems to be how to implement a Fuzzy Logic system. These have been around for some time and you can undoubtedly pick up a library for the common programming languages quite easily.
You could use a struct and handle the operations manualy. Otherwise, no a variable only has 1 value at a time.
A variable is nothing more than an address into memory. That means a variable describes exactly one place in memory (length depending on the type). So as long as we have no "quantum memory" (and we dont have it, and it doesnt look like we will have it in near future), the answer is a NO.
If you want to program and to modell this behaviour, your way would be to use a an array (with length equal to the number of max. multiple values). With this comes the increased runtime, hence the computations must be done on each of the values (e.g. x+y, must compute with 2 different values x1+y1, x2+y2, x1+y2 and x2+y1).
In Perl , you can .
If you use Scalar::Util , you can have a var take 2 values . One if it's used in string context , and another if it's used in a numerical context .