howto exclude elements from sorted array which are present in other sorted array
hi all, I have 2 sorted arrays arr1 & arr2 (ascending order, for example [1,2,5,8] and [3,5], but length may be thousands, so I need simpliest way, not costly). Howto obtain arr3 that consists of elements present in arr1 but absent in arr2? Of course, I can write something by myself, like arr3 = [x for x in arr1 if not x in arr2] but maybe already written routines are present in numpy? (that use sort)
Usually arr2 is much more small than arr1, typical former size is 10-20 and typical latter size can be 1000-10000
Thank you in advance, D.
thanks all, I have solved the problem dmitrey wrote:
hi all, I have 2 sorted arrays arr1 & arr2 (ascending order, for example [1,2,5,8] and [3,5], but length may be thousands, so I need simpliest way, not costly). Howto obtain arr3 that consists of elements present in arr1 but absent in arr2? Of course, I can write something by myself, like arr3 = [x for x in arr1 if not x in arr2] but maybe already written routines are present in numpy? (that use sort)
Usually arr2 is much more small than arr1, typical former size is 10-20 and typical latter size can be 1000-10000
Thank you in advance, D. _______________________________________________ Numpy-discussion mailing list Numpy-discussion@scipy.org http://projects.scipy.org/mailman/listinfo/numpy-discussion
On 5/29/07, dmitrey openopt@ukr.net wrote:
hi all, I have 2 sorted arrays arr1 & arr2 (ascending order, for example [1,2,5,8] and [3,5], but length may be thousands, so I need simpliest way, not costly). Howto obtain arr3 that consists of elements present in arr1 but absent in arr2? Of course, I can write something by myself, like arr3 = [x for x in arr1 if not x in arr2] but maybe already written routines are present in numpy? (that use sort)
Usually arr2 is much more small than arr1, typical former size is 10-20 and typical latter size can be 1000-10000
count = arr2.searchsorted(arr1, side='right') - arr2.searchsorted(arr1, side='left') arr3 = arr1[count == 0]
Chuck
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