----- Original Message -----
> From: Peter Otten <__pete...@web.de> > To: tutor@python.org > Cc: > Sent: Sunday, January 18, 2015 4:38 AM > Subject: Re: [Tutor] selecting data from a list > > Colin Ross wrote: > >> Hi all, >> >> I am attempting to isolate a certain subset of data from the list > "a" and >> then turn it into any array. To do so, I have written the following code: >> >> import numpy as np >> >> a = [0,1,2,3,4,5,6,7,8,9,10] >> b = [10,20,30,40,50,60,70,80,90,100,110] >> >> for a in range(len(a)): >> if a > 5: >> print a >> >> a_1 = np.array(a) >> >> print a_1 >> >> The output is as follows: >> >> 6 >> 7 >> 8 >> 9 >> 10 >> 10 >> >> >> As you can see, when I attempt to turn the list of numbers 6 through 10 >> into an array I am left with it only printing out 10... >> >> The desired result is: [6,7,8,9,10} >> >> Any guidance would be greatly appreciated. > > I have a hunch that you may be looking for slicing: > >>>> a = [0,1,2,3,4,5,6,7,8,9,10] >>>> b = [10,20,30,40,50,60,70,80,90,100,110] >>>> a[6:] > [6, 7, 8, 9, 10] >>>> b[3:] > [40, 50, 60, 70, 80, 90, 100, 110] > > If I'm right you should really work through a tutorial. If Peter is right about his hunch, then ignore the following. If not, then you could use a Boolean array to do the selection: >>> import numpy as np >>> arr = np.arange(11) >>> arr array([ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]) >>> arr > 5 array([False, False, False, False, False, False, True, True, True, True, True], dtype=bool) >>> arr[arr > 5] array([ 6, 7, 8, 9, 10]) Regards, Albert-Jan _______________________________________________ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
