Hi, Thanks for your help. I tried np.diff() before, but the result looked like this:
RESULT = [1, 1, 1, 1] So I was thinking that np.diff() doesn't iterate over the values of the array. So I gave the for-loop a try. Now, seeing your code below, I realized that my mistake was that I used ARRAY = [0, 1, 2, 3, 4, 5] for the calculations... Stupid me. 2010/1/2 Emmanuelle Gouillart <[email protected]>: > Hello Manuel, > > the discrete difference of a numpy array can be written in a very > natural way, without loops. Below are two possible ways to do it: >>>> a = np.arange(10)**2 >>>> a > array([ 0, 1, 4, 9, 16, 25, 36, 49, 64, 81]) >>>> a[1:] - a[:-1] > array([ 1, 3, 5, 7, 9, 11, 13, 15, 17]) >>>> np.diff(a) # another way to calculate the difference > array([ 1, 3, 5, 7, 9, 11, 13, 15, 17]) > > The error in the example you give is due to the fact that you iterate > over len(ARRAY), which is an integer, hence not an iterable object. You > should write ``for i in range(len(ARRAY))`` instead. > > Cheers, > > Emmanuelle > > On Sat, Jan 02, 2010 at 11:23:13AM +0100, Manuel Wittchen wrote: >> Hi, > >> I want to calculate the difference between the values of a >> numpy-array. The formula is: > >> deltaT = t_(n+1) - t_(n) > >> My approach to calculate the difference looks like this: > >> for i in len(ARRAY): >> delta_t[i] = ARRAY[(i+1):] - ARRAY[:(len(ARRAY)-1)] > >> print "result:", delta_t > >> But I get a TypeError: >> File "./test.py", line 19, in <module> >> for i in len(ARRAY): >> TypeError: 'int' object is not iterable > >> Where is the mistake in the code? > >> Regards and a happy new year, >> Manuel Wittchen >> _______________________________________________ >> NumPy-Discussion mailing list >> [email protected] >> http://mail.scipy.org/mailman/listinfo/numpy-discussion > _______________________________________________ > NumPy-Discussion mailing list > [email protected] > http://mail.scipy.org/mailman/listinfo/numpy-discussion > _______________________________________________ NumPy-Discussion mailing list [email protected] http://mail.scipy.org/mailman/listinfo/numpy-discussion
