First, I apologize for the long script. It's if anyone wants to see the
issue first hand. The problem is that when I use twinx() to plot two
different functions on the same axes, the legend from the first part is
overwritten by the grid lines of the second part (after the twinx()
statement). As you can see in the Plot function, I tried to use the
zorder to have the first legend drawn at the end but that doesn't work.
I can see two possibilities -
1) I still don't know how to use zorder, or ...
2) the twinx() statement somehow causes the zorder process to get reset
so that the first legend always gets drawn before the second function is
plotted.
Thanks for any help,
Wayne
#FilterPlot.py
from pylab import *
pico,micro,meg,gig = 1e-12,1e-6,1000000.,1.E9
NumPts,SaveFile = 2**10,1
def MakeTicks(Low,High,fudge=0):
K,up,down,Ticks,Inc = 1.,10.,0.1,[],1.
while (High-Low) <= up:
High,Low = High*up,Low*up
K *= up
while (High-Low) >= up*up:
High,Low = High*down,Low*down
K *= down
if int(fudge): High += (High-Low)*.05
Delta,Inc = High-Low,2.
if Delta > 20.: Inc = 5.
if Delta > 55.: Inc = 10.
I,inc,Min,Max = 0,Inc/K,Low/K,High/K
Ticks.append(inc*float(int(Low/Inc)))
if Ticks[0] > Min: Ticks[0] -= inc
while Ticks[-1] <= Max:
I += 1
Ticks.append(Ticks[0]+float(I)*inc)
return Ticks
def Step(Input,df):
t,v,dt,Out = [],[],1./(2.*NumPts*df),0.
for I in range(0,len(Input)/4,1):
t.append(float(I)*dt*1000.)
Out += Input[I].real
v.append(Out) # integrate impulse response
return [t,v]
def Impulse(Input,df):
t,v,dt,Out = [],[],1./(2.*NumPts*df),0.
for I in range(0,len(Input)/4,1):
t.append(float(I)*dt*1000.) # so the time scale is in nanoseconds
v.append(Input[I].real*1000.)
return [t,v]
def TransFcn(Rs,C1,L2,C3,L4,C5,Name,Resp=0):
B = [1.]
B.append(Rs*(C1+C3+C5))
B.append(L2*C3+(L4+L2)*C5)
B.append(Rs*(L2*C1*(C3+C5)+L4*C5*(C1+C3)))
B.append(L2*L4*C3*C5)
B.append(Rs*L2*L4*C1*C3*C5) #for K in range(6): print 'D['+str(K)+'] =
',D[K]
Mag,Arg,Dly,Freq,Xfer,f,unwrap = [],[],[],[],[],0.,0.
Fmax = round(16.*B[0]/(B[1]*meg),0) # Want it in MHz (100 nsec -> 160 MHz)
df = Fmax/float(NumPts)
while f < Fmax: # Gives a sequence length of NumPts
Freq.append(f)
w = 2.*pi*f*meg # w in radians/sec
w2 = w*w
w4 = w2*w2
Re,Im = B[0]-w2*B[2]+w4*B[4],w*(B[1]-w2*B[3]+w4*B[5])
cpx = 1./complex(Re,Im)
mag,arg = abs(cpx),-arctan2(Im,Re)
Xfer.append(cpx) # For fft submission
Mag.append(mag)
Arg.append(180./pi*arg)
Dly.append(gig*((B[1]-3.*w2*B[3]+5.*w4*B[5])*Re \
+ w*(2.*B[2]-4.*w2*B[4])*Im)/(Re*Re+Im*Im)) # nanoseconds
f += df
PlotFile = 'FilterResponse.png'
Plot(Freq,Xfer,Mag,Dly,Name,Resp,df)
if SaveFile:
savefig(PlotFile,dpi=300,facecolor='w',edgecolor='w')
def Plot(Freq,Xfer,Mag,Dly,Name,Resp,df):
RespType,Which = {0:'Impulse',1:'Step'},{0:Impulse,1:Step}
K = NumPts/8 # To expand interesting portion
Freq,Mag,Dly = Freq[:K],Mag[:K],Dly[:K]
xLabel,yLabel1,yLabel2 = 'Frequency (MHz)','Magnitude','Delay (nsec)'
Haxis = MakeTicks(Freq[0],Freq[-1],0)
PlotTitle = Name + ' Transfer Function'
PlotList1,PlotList2 = ['Mag'],['Delay']
figure(figsize=(6,4.5),facecolor='w',dpi=100)
axes([.095,.09,.80,.85],axisbg='1.0')
grid(True,ls='-',color=(0.,0.,.65),alpha=0.5,lw=.35)
plot(Freq,Mag,'b-',lw=1.0)
Vaxis = MakeTicks(min(Mag),max(Mag),1)
axis([Haxis[0],Haxis[-1],Vaxis[0],Vaxis[-1]])
title(PlotTitle)
ylabel(yLabel1)
xticks(Haxis)
yticks(Vaxis)
l1 = legend(PlotList1,loc=(.76,.92))
l1.zorder = 99
m1 = l1.get_frame()
m1.set_linewidth(0)
m1.set_facecolor('0.95')
twinx()
g2 = grid(True,ls='-',color=(.65,0.,0.),alpha=0.5,lw=.35)
#g2.zorder = 0 This gives an error
plot(Freq,Dly,'r-',lw=1.0)
Vaxis = MakeTicks(min(Dly),max(Dly),1)
axis([Haxis[0],Haxis[-1],Vaxis[0],Vaxis[-1]])
xlabel(xLabel)
ylabel(yLabel2)
xticks(Haxis)
yticks(Vaxis)
l2 = legend(PlotList2,loc=(.76,.86))
l2.zorder = 100
m2 = l2.get_frame()
m2.set_linewidth(0)
m2.set_facecolor('0.95')
def Main():
Rs = float(1000)
C1,C3,C5 = pico*float(6.67),pico*float(31),pico*float(62.3)
L2,L4 = micro*float(19.5),micro*float(42.1),
TransFcn(Rs,C1,L2,C3,L4,C5,'Bessel',1)
show()
try:
Main()
finally:
print '\'FilterPlot.py\' is finished.'
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