matplotlib - pyplot and semilogarithmic scale: how to draw a circle with transform -

-

i want have circle in plot made pyplot, need use log scale on x axis.

i do:

ax = plt.axes()  point1 = plt.circle((x,y), x, color='r',clip_on=false,                      transform = ax.transaxes, alpha = .5)  plt.xscale('log')  current_fig = plt.gcf()  current_fig.gca().add_artist(point1)

as see, want radius of circle equal x coordinate.

my problem if use, written here, transaxes, circle circle (otherwise stretched on x , looks ellipse cut in half), x coordinate 0. if, on other hand, use transdata instead of transaxes, correct value x coordinate, circle stretched again , cut in half.

i don't mind stretching don't cutting, want @ least full ellipse.

any idea how obtain want?

probably easiest way use plot marker instead of circle. example:

ax.plot(x,y,marker='o',ms=x*5,mfc=(1.,0.,0.,0.5),mec='none')

this give circle 'circular' , centred on correct x,y coordinate, although size bear no relationship x , y scales. if care centre position can mess around ms= until looks right.

a more general way construct new composite transformation circle - should take @ this tutorial on transformations. basically, transformation figure data space constructed this:

transdata = transscale + (translimits + transaxes)

where transscale handles nonlinear (e.g. logarithmic) scaling of data, translimits maps x- , y-limits of data unit space of axes, , transaxes maps corners of axes bounding box display space.

you want keep circle looking circle/ellipse (i.e. not distort according logarithmic scaling of x-axis), still want translate correct centre location in data coordinates. in order that, can construct scaled translation, combine translimits , transaxes:

from matplotlib.transforms import scaledtranslation  ax = plt.axes(xscale='log') x,y = 10,0 ax.set_ylim(-11,11) ax.set_xlim(1e-11,1e11)  # use axis scale tform figure out how far translate  circ_offset = scaledtranslation(x,y,ax.transscale)  # construct composite tform circ_tform = circ_offset + ax.translimits + ax.transaxes  # create circle centred on origin, apply composite tform circ = plt.circle((0,0),x,color='r',alpha=0.5,transform=circ_tform) ax.add_artist(circ) plt.show()

obviously scaling in x-axis going bit weird , arbitrary - you'll need play around how construct transformation in order want.


Comments

Post a Comment

Popular posts from this blog

c# - How Configure Devart dotConnect for SQLite Code First? -

-
can configure following sample code ? when run following code, error : no entity framework provider found ado.net provider invariant name 'devart.data.sqlite' setting in machine.config <system.data> <dbproviderfactories> <add name="dotconnect sqlite" invariant="devart.data.sqlite" description="devart dotconnect sqlite" type="devart.data.sqlite.sqliteproviderfactory, devart.data.sqlite, version=4.6.287.0, culture=neutral, publickeytoken=09af7300eec23701" /> </dbproviderfactories> </system.data> after add below block code in app.config <?xml version="1.0"?> <configuration>   <configsections> <!-- more information on entity framework configuration, visit http://go.microsoft.com/fwlink/?linkid=237468 --> <section name="entityframework" type="system.data.entity.internal.configfile.entityframeworksection, entit...
Read more

java - Copying object fields -

-
what best way of copying classes when need have 2 independent variables? have simple class: public class myclass { boolean = false; string b= "not empty"; } do need make method : assign(myclass data ) { a= data.a; b= data.b; } is there automatic method copy (duplicate) objects in java? do need make method : pretty close. instead of making method, should make constructor. such constructors called copy constructor , , create them this: myclass(myclass data) { = data.a; b = data.b; } and create copy of instance, use constructor this: myclass obj1 = new myclass(); myclass obj2 = new myclass(obj1); copy constructor can tedious : using copy constructor create deep-copy can tedious, when class has mutable fields. in case, assignment create copy of reference, , not object itself. have create copy of fields (if want deep copy). can go recursive. a better way create deep copy serialize , deserialize object. why not use clone()? ...
Read more

c++ - Clear the memory after returning a vector in a function -

-
i have function processes , stores lot of data in , returns results vector of class. amount of data stored in function tremendous , want clear storage memory of function after finished job. necessary (does function automatically clear memory) or should clear memory function? update: vector<customers> process(char* const *filename, vector<int> id) { vector<customers> list_of_customers; (perform actions) return list_of_customers; } variables defined locally within function automatically released @ end of function scope. destructors objects called, should free memory allocated objects (if objects coded correctly). example of such object std::vector . anything you've allocated new must have corresponding delete release storage. try avoid doing own allocation , use raii instead, i.e. containers or smart pointers.
Read more