matplotlib: TypeError: a float is required

[Andi Clemens]

Hi,

everytime I try to plot a bar with matplotlib I get the following error 
message:
Traceback (most recent call last):
   File "bar_stacked.py", line 13, in ?
     p1 = bar(ind, menMeans,   width, color='r', yerr=womenStd)
   File "/usr/lib/python2.4/site-packages/matplotlib/pylab.py", line 
1641, in bar
     ret =  gca().bar(*args, **kwargs)
   File "/usr/lib/python2.4/site-packages/matplotlib/axes.py", line 
2485, in bar
     xerr = asarray([xerr]*nbars, Float)
   File "/usr/lib/python2.4/site-packages/Numeric/Numeric.py", line 134, 
in asarray
     return multiarray.array(a, typecode, copy=0, savespace=savespace)
TypeError: a float is required


So I guess it has something to do with Numeric.py, but I can't figure 
out what the problem is. I tried to google but found nothing...

Anyone has the same problem? I can plot all kinds of graphics with 
matplotlib, but the only type I'm interested in (bars) will not work.

I tried the examples coming with matplotlib, but even those don't work.

Here is the example code which produces the above error:
#!/usr/bin/env python
# a stacked bar plot with errorbars
from pylab import *

N = 5
menMeans   = (20, 35, 30, 35, 27)
womenMeans = (25, 32, 34, 20, 25)
menStd     = (2, 3, 4, 1, 2)
womenStd   = (3, 5, 2, 3, 3)
ind = arange(N)    # the x locations for the groups
width = 0.35       # the width of the bars: can also be len(x) sequence

p1 = bar(ind, menMeans,   width, color='r', yerr=womenStd)
p2 = bar(ind, womenMeans, width, color='y',
          bottom=menMeans, yerr=menStd)

ylabel('Scores')
title('Scores by group and gender')
xticks(ind+width/2., ('G1', 'G2', 'G3', 'G4', 'G5') )
yticks(arange(0,81,10))
legend( (p1[0], p2[0]), ('Men', 'Women') )

show()


Anyone has matplotlib installed and gets the same error?
I need to create some charts for a project I do at work, so maybe there 
are other modules out there creating charts??

Andi

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