Matplotlib: Formattazione delle date sull'asse x in un grafico a barre 3D

Question

Dato questo 3D bar graph sample code, come convertire i dati numerici nell'asse x in stringhe di data/ora formattate? Ho tentato di utilizzare la funzione ax.xaxis_date() senza successo. Ho anche provato ad usare plot_date(), che non sembra funzionare per i grafici a barre 3D. Ecco una versione modificata del codice di esempio per illustrare quello che sto cercando di fare:

from mpl_toolkits.mplot3d import Axes3D 
import matplotlib.pyplot as plt 
import numpy as np 
import matplotlib.dates as dates 

dates = [dates.date2num(datetime.datetime(2009,3,12)), 
     dates.date2num(datetime.datetime(2009,6,9)), 
     dates.date2num(datetime.datetime(2010,1,1)), 
     #etc... 
     ] 

fig = plt.figure() 
ax = Axes3D(fig) 
for c, z in zip(['r', 'g', 'b', 'y'], [30, 20, 10, 0]): 
    xs = np.array(dates) 
    ys = np.random.rand(20) 
    ax.bar(xs, ys, zs=z, zdir='y', color=c, alpha=0.8) 

ax.set_xlabel('Date & Time') 
ax.set_ylabel('Series') 
ax.set_zlabel('Amount') 

plt.show() 

alt text http://matplotlib.sourceforge.net/_images/bars3d_demo1.png

Answer 1

Ci potrebbe essere una certa confusione qui, l'Axes3D ha le proprietà w_xaxis, w_yaxis e w_zaxis per i axises invece del solito xaxix, yaxis, ecc.

UPDATE Ora usa la funzione per formattare le etichette.

from mpl_toolkits.mplot3d import Axes3D 
import matplotlib.pyplot as plt 
import numpy as np 
import matplotlib.dates as dates 
import datetime, random 
import matplotlib.ticker as ticker 

def random_date(): 
     date = datetime.date(2008, 12,01) 
     while 1: 
     date += datetime.timedelta(days=30) 
     yield (date) 

def format_date(x, pos=None): 
    return dates.num2date(x).strftime('%Y-%m-%d') #use FuncFormatter to format dates 

r_d = random_date() 
some_dates = [dates.date2num(r_d.next()) for i in range(0,20)] 

fig = plt.figure() 
ax = Axes3D(fig,rect=[0,0.1,1,1]) #make room for date labels 

for c, z in zip(['r', 'g', 'b', 'y'], [30, 20, 10, 0]): 
    xs = np.array(some_dates) 
    ys = np.random.rand(20) 
    ax.bar(xs, ys, zs=z, zdir='y', color=c, alpha=0.8,width=8) 

ax.w_xaxis.set_major_locator(ticker.FixedLocator(some_dates)) # I want all the dates on my xaxis 
ax.w_xaxis.set_major_formatter(ticker.FuncFormatter(format_date)) 
for tl in ax.w_xaxis.get_ticklabels(): # re-create what autofmt_xdate but with w_xaxis 
     tl.set_ha('right') 
     tl.set_rotation(30)  

ax.set_ylabel('Series') 
ax.set_zlabel('Amount') 

plt.show() 

produce:

alt text http://www.imagechicken.com/uploads/1265570252049424000.png