Example #1
0
    def __init__(self, **options):
        # inherit from the base class
        Group.__init__(self, **options)

        # process the options if any
        self.fg = options.get("fg", self.fg)
        self.bg = options.get("bg", self.bg)
        self.height = options.get("height", self.height)
        self.width = options.get("width", self.width)
        self.angle = options.get("angle", self.angle)

        # make the laser
        laser = Group()
        laser.append(
            Path(P(0, 0),
                 P(0, self.height),
                 P(self.width, self.height),
                 P(self.width, 0),
                 closed=1,
                 fg=self.fg,
                 bg=self.bg))

        # rotate if necessary
        laser.rotate(self.angle, p=laser.bbox().c)

        self.append(laser)
Example #2
0
    def __init__(self, **options):
        # inherit from base class
        Group.__init__(self, **options)

        # process the options if any
        self.width = options.get("width", self.width)
        self.height = options.get("height", self.height)
        self.angle = options.get("angle", self.angle)
        self.fg = options.get("fg", self.fg)
        self.bg = options.get("bg", self.bg)

        # now make the phase shifter
        ps = Path(
            P(0, 0),
            P(self.width / 2.0, self.height),
            P(self.width, 0),
            closed=1,
            fg=self.fg,
            bg=self.bg,
        )

        # rotate if necessary
        if self.angle != 0:
            ps.rotate(self.angle, p=ps.bbox().c)

        self.append(ps)
Example #3
0
    def __init__(self, **options):
        # inherit from the base class
        Group.__init__(self, **options)

        # process the options if any
        self.fg = options.get("fg", self.fg)
        self.bg = options.get("bg", self.bg)
        self.height = options.get("height", self.height)
        self.thickness = options.get("thickness", self.thickness)
        self.angle = options.get("angle", self.angle)

        # make the beam splitter
        bs = Group()
        bs.append(
            Path(P(0, 0),
                 P(0, self.height),
                 P(self.thickness, self.height),
                 P(self.thickness, 0),
                 closed=1,
                 fg=self.fg,
                 bg=self.bg))

        # rotate if necessary
        bs.rotate(self.angle, p=bs.bbox().c)

        self.append(bs)
Example #4
0
def SWAP(**options):
    """
    Swap gate
    """
    x = Group(Path(P(-.1, .1), P(.1, -.1)), Path(P(-.1, -.1), P(.1, .1)))
    options['controlobj'] = options.get('controlobj', x)
    return Gate(x, **options)
Example #5
0
    def __init__(self, **options):
        # inherit from the base class
        Group.__init__(self, **options)

        # process the options if any
        self.fg = options.get("fg", self.fg)
        self.bg = options.get("bg", self.bg)
        self.height = options.get("height", self.height)
        self.width = options.get("width", self.width)
        self.angle = options.get("angle", self.angle)

        # make the free space
        fs = Group()
        fs.append(
            Path(P(0, 0),
                 P(0, self.height),
                 P(self.width, self.height),
                 P(self.width, 0),
                 closed=1,
                 fg=self.fg,
                 bg=self.bg,
                 dash=Dash()))

        # rotate if necessary
        fs.rotate(self.angle, p=fs.bbox().c)

        self.append(fs)
Example #6
0
def NOT(**options):
    """
    NOT gate
    """
    r = .2
    return Gate(
        Group(Circle(r=r), Path(P(0, r), P(0, -r)), Path(P(-r, 0), P(r, 0))),
        **options)
Example #7
0
 def set(self, y, e, w):
     """
     Set the east, west and y postions of the QWire
     """
     path = Path(P(w, y),
                 P(e, y),
                 fg=self.fg,
                 linewidth=self.linewidth,
                 dash=self.dash)
     self.append(path)
     return self
Example #8
0
    def __init__(self, **options):
        # initialise the base class
        Gate.__init__(self, **options)

        # process the options if any
        self.height = options.get("height", self.height)
        self.width = options.get("width", self.width)
        self.angle = options.get("angle", self.angle)
        self.pinLength = options.get("pinLength", self.pinLength)
        self.fg = options.get("fg", self.fg)
        self.bg = options.get("bg", self.bg)
 
        # now draw the gate
        buff = 0
        pl = self.pinLength
        pinEdgeDist = 0.1*self.height
        bodyHeight = self.height
        bodyWidth = self.width - 2.0*pl
        rad = 0.1

        gateBody = Group(
                Path( 
                    P(pl, buff+0), 
                    P(pl, buff+bodyHeight), 
                    P(pl+0.707106781*bodyWidth, buff+bodyHeight/2.), 
                    P(pl, buff+0)
                    )
                )
        gatePinIn1 = Path(
                P(0, bodyHeight-pinEdgeDist), 
                P(pl, bodyHeight-pinEdgeDist))
        gatePinIn2 = Path(
                P(0, pinEdgeDist), 
                P(pl, pinEdgeDist))
        gatePinOut = Group(
                Circle(w=gateBody.e, r=rad), 
                Path(
                    gateBody.e+P(2.*rad, 0), 
                    gateBody.e+P(2.*rad+pl, 0))
                )

        # collect the objects together
        obj = Group(gateBody, gatePinIn1, gatePinIn2, gatePinOut)

        # apply the colours
        obj.apply(fg=self.fg, bg=self.bg)

        # rotate if necessary
        if self.angle != 0.0:
            obj.rotate(self.angle, p=obj.c)

        # now set the object to myself
        self.append(obj)
Example #9
0
    def __init__(self, **options):
        # initialise the base class
        Gate.__init__(self, **options)

        # process the options if any
        self.height = options.get("height", self.height)
        self.width = options.get("width", self.width)
        self.angle = options.get("angle", self.angle)
        self.pinLength = options.get("pinLength", self.pinLength)
        self.fg = options.get("fg", self.fg)
        self.bg = options.get("bg", self.bg)
 
        # now draw the gate
        pl = self.pinLength
        pinEdgeDist = 0.1*self.height
        pinBackDist = -0.08*self.width
        bodyHeight = self.height
        bodyWidth = self.width - 2.0*pl
        rad = 0.1

        gateBody = Group(
                Path( 
                    P(-pinBackDist, -pinEdgeDist), 
                    C(90, 225),
                    P(1.25*bodyWidth, bodyHeight/2.0), 
                    C(-45, 90),
                    P(-pinBackDist, bodyHeight+pinEdgeDist), 
                    C(140, 40),
                    closed=1,
                    )
                )
        gatePinIn1 = Path(
                P(0, bodyHeight-pinEdgeDist), 
                P(pl, bodyHeight-pinEdgeDist))
        gatePinIn2 = Path(
                P(0, pinEdgeDist), 
                P(pl, pinEdgeDist))
        gatePinOut = Group( 
                Circle(w=gateBody.e, r=rad), 
                Path(
                    gateBody.e+P(0.2, 0), 
                    gateBody.e+P(pl+0.2, 0)),
                )

        # collect the objects together
        obj = Group(gateBody, gatePinIn1, gatePinIn2, gatePinOut)

        # apply the colours
        obj.apply(fg=self.fg, bg=self.bg)

        # rotate if necessary
        if self.angle != 0.0:
            obj.rotate(self.angle, p=obj.c)

        # nwo set the object to myself
        self.append(obj)
Example #10
0
    def __init__(self, **options):
        Group.__init__(self, **options)
        p = Group()

        self.fg = options.get("fg", self.fg)
        self.bg = options.get("bg", self.bg)
        if self.width > self.height:
            p.append(
                Path(P(0, 0),
                     P(0, self.height),
                     P(self.width - self.height / 2.0, self.height),
                     C(90, 0),
                     P(self.width, self.height / 2.0),
                     C(180, 90),
                     P(self.width - self.height / 2.0, 0),
                     fg=self.fg,
                     bg=self.bg,
                     closed=1))
        else:
            p.append(
                Path(P(0, 0),
                     P(0, self.height),
                     C(90, 0),
                     P(self.width, self.height / 2.0),
                     C(180, 90),
                     closed=1))

        # rotate if necessary
        self.angle = options.get("angle", self.angle)
        p.rotate(self.angle, p=p.bbox().c)

        self.append(p)
Example #11
0
def Detector(e=P(0, 0), height=1.0, label=None):
    """
    Detector

    @param height: height of detector
    @type height: float

    @param label: detector label
    @type label: string
    """
    if label is not None:
        return Group(Path(e - P(0, height / 2.0), e + P(0, height / 2.0)),
                     Circle(c=e, r=height / 2.0, start=0, end=180), label)
    else:
        return Group(Path(e - P(0, height / 2.0), e + P(0, height / 2.0)),
                     Circle(c=e, r=height / 2.0, start=0, end=180))
Example #12
0
    def __init__(self, tobj, **options):

        Group.__init__(self, **options)

        # XXX should we take a copy???
        self.targetobj = tobj.copy()

        if self.controlobj is None:
            self.controlobj = Dot(r=self.dot_r)

        # fix up target and control points
        if type(self.target) in (type(()), type([])):
            pass
        elif isinstance(self.target, P):
            self.target = [self.target]
        elif self.target is None:
            self.target = [P(0, 0)]
        else:
            raise ValueError, "don't understand target structure for Gate"

        if type(self.control) in (type(()), type([])):
            pass
        elif isinstance(self.control, P):
            self.control = [self.control]
        elif self.control is None:
            self.control = []
        else:
            raise ValueError, "don't understand control structure for Gate"

        self._make()
Example #13
0
def CZGate(c=P(0, 0), controlDist=1.0, direction="up", side=0.5):
    """
    Controlled Z gate

    @param controlDist: distance to the control
    @type controlDist: float

    @param direction: in which direction is the control?  up/down
    @type direction: string

    @param side: length of the box side
    @type side: float
    """
    if direction is "up":
        return Group(
            Circle(c=c + P(0, controlDist), r=0.065, bg=Color("black")),
            Path(c + P(0, side / 2.), c + P(0, controlDist)),
            Rectangle(width=side, height=side, c=c, bg=Color("white")),
            TeX(r'Z', c=c))
    elif direction is "down":
        return Group(
            Circle(c=c - P(0, controlDist), r=0.65, bg=Color("black")),
            Path(c - P(0, side / 2.), c - P(0, controlDist)),
            Rectangle(width=side, height=side, c=c, bg=Color("white")),
            TeX(r'Z', c=c))
Example #14
0
def ZGate(c=P(0, 0), side=0.5):
    """
    Z gate

    @param side: length of the box side
    @type side: float
    """
    return Group(Rectangle(width=side, height=side, c=c, bg=Color("white")),
                 TeX(r'Z', c=c))
Example #15
0
def Cnot(c=P(0, 0), targetDist=1.0, direction="up"):
    """
    Controlled NOT gate

    @param targetDist: distance to the target rail
    @type targetDist: float

    @param direction: in which direction is the target rail?  up/down
    @type direction: string
    """
    if direction is "up":
        return Group(Circle(r=0.06, bg=Color("black"), c=c),
                     Circle(r=0.2, c=c + P(0, targetDist)),
                     Path(c, c + P(0, targetDist + 0.2)))
    elif direction is "down":
        return Group(Circle(r=0.06, bg=Color("black"), c=c),
                     Circle(r=0.2, c=c + P(0, -targetDist)),
                     Path(c, c + P(0, -targetDist - 0.2)))
Example #16
0
    def __init__(self, **options):
        # inherit from the base class
        Group.__init__(self, **options)

        # process the options if any
        self.fg = options.get("fg", self.fg)
        self.bg = options.get("bg", self.bg)
        self.height = options.get("height", self.height)
        self.thickness = options.get("thickness", self.thickness)
        self.angle = options.get("angle", self.angle)
        self.type = options.get("type", self.type)

        # determine what type of lens to make
        if self.type == "convex":
            leftCurveAngle = -30
            rightCurveAngle = -30
        elif self.type == "concave":
            leftCurveAngle = 30
            rightCurveAngle = 30
        else:
            print "Unknown lens type, defaulting to concave"
            leftCurveAngle = 30
            rightCurveAngle = 30

        # make the lens
        lens = Group()
        lens.append(
            Path(
                P(0, 0),
                C(leftCurveAngle, 180 - leftCurveAngle),
                P(0, self.height),
                P(self.thickness, self.height),
                C(-180 + rightCurveAngle, -rightCurveAngle),
                P(self.thickness, 0),
                closed=1,
                fg=self.fg,
                bg=self.bg,
            ))

        # rotate if necessary
        lens.rotate(self.angle, p=lens.bbox().c)

        self.append(lens)
Example #17
0
    def __init__(self, **options):
        # intitialise base class
        Group.__init__(self, **options)

        self.length = 3.0
        self.width = 1.0
        self.angle = 0.0
        self.pinLength = 0.5
        self.fg = Color(0)
        self.bg = Color(1)

        # process the options if any
        self.length = options.get("length", self.length)
        self.width = options.get("width", self.width)
        self.angle = options.get("angle", self.angle)
        self.pinLength = options.get("pinLength", self.pinLength)
        self.fg = options.get("fg", self.fg)
        self.bg = options.get("bg", self.bg)

        pinIn = Group(
                Path( 
                    P(0, 0), 
                    P(self.pinLength, 0)
                    )
                )
        resistor = Rectangle(w=pinIn.e, width=self.length, height=self.width)
        pinOut = Path(
                resistor.e, 
                resistor.e+P(self.pinLength, 0))

        # collect the objects together
        obj = Group(pinIn, pinOut, resistor)

        # apply the colours
        obj.apply(fg=self.fg, bg=self.bg)

        # rotate if necessary
        if self.angle != 0.0:
            obj.rotate(self.angle, p=obj.c)

        # return object to myself
        self.append(obj)
Example #18
0
    def setgate(self, gate, target, control=None):
        """
        Set the gate in the assembly
        """

        # if it already an instance this will have no effect
        # otherwise create an instance
        gate = apply(gate)

        # XXX multi target qubits
        gate.settarget(P(0, -target))

        if isinstance(control, (IntType, FloatType)):
            gate.setcontrol(P(0, -control))
        elif isinstance(control, (TupleType, ListType)):
            tmp = []
            for cc in control:
                tmp.append(P(0, -cc))
            apply(gate.setcontrol, tmp)

        return gate
Example #19
0
    def __init__(self, obj, **options):
        bbox = obj.bbox()

        pad = .1
        r = max(bbox.width + 2 * pad, bbox.height + 2 * pad) / 2.0

        self.width = 2.0 * r
        self.height = 2.0 * r

        self.bg = options.get('bg', Color(1))
        if options.has_key('bg'):
            del options['bg']

        apply(Group.__init__, (self, ), options)
        apply(Area.__init__, (self, ), options)

        obj.c = P(r, r)

        self.append(
            Circle(r=r, bg=self.bg, c=P(r, r)),
            obj,
        )
Example #20
0
def cbox(obj, x, yt, yc):
    '''
    @param obj: the object to put a box around
    @type obj: object

    @param x: x position of line and centre of box
    @type x: float

    @param yt: y position of target
    @type yt: float

    @param yc: y position of control
    @type yc: float

    @return: a controlled box
    '''
    g = Group(
        Path(P(x, yt), P(x, yc)),
        Boxed(obj, c=P(x, yt), bg=Color(1)),
        Dot(P(x, yc)),
    )
    return g
Example #21
0
    def __init__(self, **args):
        Group.__init__(self, **args)

        h = self.height
        w = self.width

        self.append(Rectangle(width=1.8 * h, height=h, bg=self.bg))

        p = Path(P(.1, .1),
                 C(0, 0),
                 P(w - .1, .1),
                 P(w - .2, .1),
                 C(0, 0),
                 P(.2, .1),
                 closed=1,
                 bg=self.mcolor,
                 fg=None)

        self.append(
            p,
            Path(P(w / 2., .1), U(self.angle, h * .9)),
        )
Example #22
0
def detector(**options):
    '''
    @return: a D shaped detector
    '''
    r = 0.3
    c = 0.65 * r
    path = [
        P(0, -r),
        P(0, r),
        C(P(c, r), P(r, c)),
        P(r, 0),
        C(P(r, -c), P(c, -r)),
        P(0, -r)
    ]
    options['bg'] = options.get('bg', Color(.8))
    options['closed'] = 1
    p = apply(Path, path, options)
    a = Area(width=r, height=2 * r, e=P(0, 0))

    return Group(a, p)
Example #23
0
    def __init__(self, object=None, **options):
        if object is not None:
            # use the object's boundingbox when width and height not supplied
            bb = object.bbox()
            w = bb.width + 2 * self.pad
            h = bb.height + 2 * self.pad

            self.width = options.get("width", max(w, self.width))
            self.height = options.get("height", max(h, self.height))
        Group.__init__(self, **options)

        if self.width > self.height:
            p = Path(P(0, 0),
                     P(0, self.height),
                     P(self.width - self.height / 2., self.height),
                     C(90, 0),
                     P(self.width, self.height / 2.),
                     C(180, 90),
                     P(self.width - self.height / 2., 0),
                     closed=1)
        else:

            p = Path(P(0, 0),
                     P(0, self.height),
                     C(90, 0),
                     P(self.width, self.height / 2.),
                     C(180, 90),
                     closed=1)

        p(bg=options.get("bg", self.bg), fg=options.get("fg", self.fg))

        self.append(p)
        if object is not None:
            # object looks better if it's slightly off centre
            # since one side is curved. pad/3 is about right
            object.c = P(self.width / 2. - self.pad / 3., self.height / 2.)
            self.append(object)
Example #24
0
    def __init__(self, **options):
        # intitialise base class
        Group.__init__(self, **options)

        self.sep = 0.25
        self.width = 1.0
        self.angle = 0.0
        self.pinLength = 0.5
        self.fg = Color(0)
        self.bg = Color(1)

        # process the options if any
        self.sep = options.get("sep", self.sep)
        self.width = options.get("width", self.width)
        self.angle = options.get("angle", self.angle)
        self.pinLength = options.get("pinLength", self.pinLength)
        self.fg = options.get("fg", self.fg)
        self.bg = options.get("bg", self.bg)

        pinIn = Group(
                Path( 
                    P(0, 0), 
                    P(self.pinLength, 0),
                    )
                )
        cap = Group( 
                Path(pinIn.e+P(0, -self.width/2.0), 
                    pinIn.e+P(0, self.width/2.0)), 
                Path(pinIn.e+P(self.sep, -self.width/2.0), 
                    pinIn.e+P(self.sep, self.width/2.0)),
                )
        pinOut = Path(
                cap.e, 
                cap.e+P(self.pinLength, 0))

        # group the objects together
        obj = Group(pinIn, pinOut, cap)

        # apply the colours
        obj.apply(fg=self.fg, bg=self.bg)

        # rotate if necessary
        if self.angle != 0.0:
            obj.rotate(self.angle, p=obj.c)

        # set the object to myself
        self.append(obj)
Example #25
0
    def background(self):
        '''
        Return background for poster
        '''
        area = self.area()

        signature = Text(
            'Created with PyScript.  http://pyscript.sourceforge.net',
            size=14,
            fg=Color(1))

        signature.se = area.se + P(-.5, .5)
        return Group(
            Rectangle(width=area.width,
                      height=area.height,
                      fg=None,
                      bg=self.bg),
            signature,
        )
Example #26
0
    def __init__(self, obj, **options):
        bbox = obj.bbox()

        pad = .1
        w = bbox.width + 2 * pad
        h = bbox.height + 2 * pad

        self.width = w
        self.height = h
        self.bg = options.get('bg', Color(1))
        if options.has_key('bg'):
            del options['bg']

        apply(Group.__init__, (self, ), options)
        apply(Area.__init__, (self, ), options)

        obj.c = P(w / 2., h / 2.)

        self.append(
            Rectangle(width=w, height=h, bg=self.bg),
            obj,
        )
Example #27
0
    def __init__(self, **options):
        # inherit from the base class
        Group.__init__(self, **options)

        # process the options if any
        self.fg = options.get("fg", self.fg)
        self.bg = options.get("bg", self.bg)
        self.length = options.get("length", self.length)
        self.thickness = options.get("thickness", self.thickness)
        self.angle = options.get("angle", self.thickness)
        self.flicks = options.get("flicks", self.flicks)

        # make the mirror itself
        mirror = Group()
        mirror.append(
            Path(P(0, 0),
                 P(0, self.length),
                 P(self.thickness, self.length),
                 P(self.thickness, 0),
                 closed=1,
                 fg=self.fg,
                 bg=self.bg))

        if self.flicks:
            # make the flicks on the back of the mirror
            flickLen = 0.15
            flicksObj = Group()
            for i in range(10):
                flicksObj.append(
                    Path(P((i + 1.0) * self.length / 10.0, self.thickness),
                         P(i * self.length / 10.0, self.thickness + flickLen),
                         fg=self.fg,
                         bg=self.bg))

            mirror.append(flicksObj)

        # rotate the mirror if necessary
        if self.angle != 0.0:
            mirror.rotate(self.angle, p=mirror.bbox().c)

        # make the mirror the current object
        self.append(mirror)
Example #28
0
def Rail(w=P(0, 0), length=1.0, labelIn=None, labelOut=None, buff=0.05):
    """
    A Rail of a quantum circuit diagram

    @param length: length of the rail
    @type length: float

    @param labelIn: input label
    @type labelIn: string

    @param labelOut: output label
    @type labelOut: string

    @param buff: buffer of space between the end of the rail and the label
    @type buff: float
    """
    if labelIn is not None and labelOut is not None:
        return Group(Path(w + P(0, 0), w + P(length, 0)),
                     TeX(labelIn, e=w - P(buff, 0)),
                     TeX(labelOut, w=w + P(buff + length, 0)))
    elif labelIn is not None and labelOut is None:
        return Group(Path(w + P(0, 0), w + P(length, 0)),
                     TeX(labelIn, e=w - P(buff, 0)))
    elif labelIn is None and labelOut is not None:
        return Group(Path(w + P(0, 0), w + P(length, 0)),
                     TeX(labelOut, w=w + P(buff + length, 0)))
    else:
        return Group(Path(w + P(0, 0), w + P(length, 0)))
Example #29
0
    def __init__(self, *gates, **options):
        self.starthang = options.get('hang', self.hang)
        self.endhang = options.get('hang', self.hang)
        Group.__init__(self, **options)

        sequence = list(gates)

        # parse the list ...
        wires = []
        named = {}
        basetime = 0
        while len(sequence) > 0:
            # the gate ...
            gate = sequence.pop(0)

            # the target ...
            t = sequence.pop(0)
            wires.append(t)

            # optional controls ...
            if len(sequence) > 0 and \
                    isinstance(sequence[0], (IntType, FloatType)):
                c = sequence.pop(0)
                wires.append(c)
            elif len(sequence) > 0 and \
                    isinstance(sequence[0], (TupleType, ListType)):
                c = sequence.pop(0)
                wires.extend(c)
            else:
                c = None

            g = self.setgate(gate, t, c)

            # optional time label ...
            if len(sequence) > 0 and isinstance(sequence[0], StringType):
                l = sequence.pop(0)
                if named.has_key(l):
                    # group already exists
                    named[l].append(g)
                else:
                    # create new named group
                    G = named[l] = Group(g)
                    self.append(G)
            else:
                self.append(g)

        L = 0
        for ii in self:
            L += ii.width + self.gatespacing
        L -= self.gatespacing

        # XXX add distribute's options
        Distribute(self, p1=P(0, 0), p2=P(L, 0))
        self.recalc_size()

        # XXX should check wires are ints

        # add wires ...
        x0 = self.w.x - self.starthang
        x1 = self.e.x + self.endhang
        if len(self.wires) == 0:
            for w in range(-min(wires), -max(wires) - 1, -1):
                wire = QWire().set(w * self.wirespacing, x0, x1)
                self.insert(0, wire)
                self.wires.append(wire)
            print self.wires
        else:
            #w=-int(min(wires))
            w = -1
            wirestmp = []
            for wire in self.wires:
                # if it already an instance this will have no effect
                # otherwise create an instance
                wire = apply(wire, ())
                wire.set(w * self.wirespacing, x0, x1)
                self.insert(0, wire)
                wirestmp.append(wire)
                w -= 1
            self.wires = wirestmp
Example #30
0
def BS(sw=P(0, 0), label=None, h=1.0):
    """
    Beam splitter; displayed as a line possibly more useful in linear optics
    quantum computation diagrams

    @param sw: location of the south-west corner of the object
    @type sw: L{P} object

    @param label: beam splitter label
    @type label: string

    @param h: beam splitter height
    @type h: float
    """
    buff = P(0, 0.1)
    b = Path(sw - buff,
             sw + P(0, h) + buff,
             sw + P(h, h) + buff,
             sw + P(h, 0) - buff,
             sw - buff,
             fg=None,
             bg=Color("white"))
    p1 = Path(sw, sw + P(h, h))
    p2 = Path(sw + P(0, h), sw + P(h, 0))
    p3 = Path(sw + P(h / 4, h / 2),
              sw + P(h, 0) + P(-h / 4, h / 2),
              linewidth=1)

    if label is not None:
        label['w'] = sw + P(h, 0) + P(-h / 4, h / 2)
        return Group(b, p1, p2, p3, label)
    else:
        return Group(b, p1, p2, p3)