This is the first time I encountered this issue since I began using Julia about a year ago. Thank you for the clarification John.
On Saturday, July 25, 2015 at 11:48:36 AM UTC-4, John Myles White wrote: > > > http://www.johnmyleswhite.com/notebook/2014/09/06/values-vs-bindings-the-map-is-not-the-territory/ > > On Saturday, July 25, 2015 at 8:13:33 AM UTC-7, Christopher Fisher wrote: >> >> I am writing a program (in .3.1) that takes a one dimensional array of >> indices (x) and creates a new one dimensional array of indices (x = y) and >> switches a given pair of elements in the new array. For some reason, the >> original array (x) changes when I change the new array (see below). >> >> In [16]: >> >> x = [1:5] >> >> y = x >> >> y[[3;4]] = y[[4;3]] >> >> [x y] >> >> Out[16]: >> >> 5x2 Array{Int64,2}: >> 1 1 >> 2 2 >> 4 4 >> 3 3 >> >> >> >> However, if I change y = x to y = x[:], the problem does not occur, even >> though x and x[:] appear to be the same type. >> >> >> In [15]: >> >> x = [1:5] >> >> y = x[:] >> >> y[[3;4]] = y[[4;3]] >> >> [x y] >> >> Out[15]: >> >> 5x2 Array{Int64,2}: >> 1 1 >> 2 2 >> 3 4 >> 4 3 >> 5 5 >> >> >> The code below shows that this does not seem to be a general property of the >> language. As in the previous cases, I define y as x and change y. >> >> >> In [13]: >> >> x = [1:5] >> >> y = x >> >> y = y*4 >> >> [x y] >> >> Out[13]: >> >> 5x2 Array{Int64,2}: >> 1 4 >> 2 8 >> 3 12 >> 4 16 >> 5 20 >> >> >> >> Certainly, I could use y = x[:] or simply change the original array. >> Nonetheless, the inconsistency seems undesirable from my point of view. Is >> this a bug? Any help would be appreciated. >> >> >>
