Happy Deer wrote: > First, I have experience in Matlab, where I can use "eval". I wonder > whether someone knows about it.
Python has an eval() function but it's use is discouraged, there is usually a better way. It would help if you would give us more context for your problem. > Second, if I just want to return data[:,1], ...data[:,-1] separately > without knowing ahead how many columns data has. What should I do? I'm assuming data is a numpy or Numeric array though it would help if you would confirm that. In [10]: from numpy import array In [11]: a = array([[1,2,3],[4,5,6]]) a.shape gives the dimensions; a.shape[1] is the second dimension In [15]: a.shape Out[15]: (2, 3) In [18]: a.shape[1] Out[18]: 3 You can use a list comprehension to make a list of the columns. In [19]: [ a[:,i] for i in range(1, a.shape[1])] Out[19]: [array([2, 5]), array([3, 6])] Note you asked for data[:,1], ...data[:,-1] which does not include the first column. Kent _______________________________________________ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor