Here's some template code for plotting histograms that don't look like bar charts, but instead have only outlines (like IDL creates).

First define a function that does the bulk of the heavy lifting.

```   1 import numpy as np
2
3 def histOutline(dataIn, *args, **kwargs):
4     (histIn, binsIn) = np.histogram(dataIn, *args, **kwargs)
5
6     stepSize = binsIn[1] - binsIn[0]
7
8     bins = np.zeros(len(binsIn)*2 + 2, dtype=np.float)
9     data = np.zeros(len(binsIn)*2 + 2, dtype=np.float)
10     for bb in range(len(binsIn)):
11         bins[2*bb + 1] = binsIn[bb]
12         bins[2*bb + 2] = binsIn[bb] + stepSize
13         if bb < len(histIn):
14             data[2*bb + 1] = histIn[bb]
15             data[2*bb + 2] = histIn[bb]
16
17     bins[0] = bins[1]
18     bins[-1] = bins[-2]
19     data[0] = 0
20     data[-1] = 0
21
22     return (bins, data)
```

Now we can make plots:

```   1
2 # Make some data to plot
3 data = randn(500)
4
5 figure(2, figsize=(10, 5))
6 clf()
7
8 ##########
9 #
10 # First make a normal histogram
11 #
12 ##########
13 subplot(1, 2, 1)
14 (n, bins, patches) = hist(data)
15
16 # Boundaries
17 xlo = -max(abs(bins))
18 xhi = max(abs(bins))
19 ylo = 0
20 yhi = max(n) * 1.1
21
22 axis([xlo, xhi, ylo, yhi])
23
24 ##########
25 #
26 # Now make a histogram in outline format
27 #
28 ##########
29 (bins, n) = histOutline(data)
30
31 subplot(1, 2, 2)
32 plot(bins, n, 'k-')
33 axis([xlo, xhi, ylo, yhi])
```

Here you can find this functionality packaged up into histOutline.py

Cookbook/Matplotlib/UnfilledHistograms (last edited 2009-07-01 22:47:50 by MarshallPerrin)