python error: no module named pylab

问题:

I am new to Python and want to use its plot functionality to create graphs. I am using ubuntu 12.04. I followed the Python installation steps from http://eli.thegreenplace.net/2011/10/10/installing-python-2-7-on-ubuntu/ but when I do

from pylab import *

I am getting this error

>>> from pylab import *
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: No module named pylab

My Python version is python 2.7. Can anybody tell me what I am missing here?

回答1:

You'll need to install numpy, scipy and matplotlib to get pylab. In ubuntu you can install them with this command:

sudo apt-get install python-numpy python-scipy python-matplotlib

If you installed python from source you will need to install these packages through pip. Note that you may have to install other dependencies to do this, as well as install numpy before the other two.

That said, I would recommend using the version of python in the repositories as I think it is up to date with the current version of python (2.7.3).

回答2:

I solved the same problem by installing "matplotlib".

回答3:

I installed python-numpy python-scipy python-matplotlib, but it didn't work for me and I got the same error. Pylab isn't recognized without matplotlib. So I used this:

from matplotlib import pylab
from pylab import *

and worked for me.

回答4:

The error means pylab is not part of the standard Python libraries. You will need to down-load it and install it. I think it's available Here They have installation instructions here

回答5:

What you've done by following those directions is created an entirely new Python installation, separate from the system Python that is managed by Ubuntu packages.

Modules you had installed in the system Python (e.g. installed via packages, or by manual installation using the system Python to run the setup process) will not be available, since your /usr/local-based python is configured to look in its own module directories, not the system Python's.

You can re-add missing modules now by building them and installing them using your new /usr/local-based Python.

回答6:

With the addition of Python 3, here is an updated code that works:

import numpy as n
import scipy as s
import matplotlib.pylab as p #pylab is part of matplotlib

xa=0.252
xb=1.99

C=n.linspace(xa,xb,100)
print(C)
iter=1000
Y = n.ones(len(C))

for x in range(iter):
    Y = Y**2 - C   #get rid of early transients

for x in range(iter): 
    Y = Y**2 - C
    p.plot(C,Y, '.', color = 'k', markersize = 2)

p.show()