python - numpy array slicing, why sometimes 2-d array and sometimes 1-d array -


my question array slicing in numpy. what's logic following behavior?

x = arange(25) x.shape = (5, 5) # results in 2-d array in rows , columns excerpted x y = x[0:2, 0:2] # results in 1-d array y2 = x[0:2, 0]

i have expected y2 2-d array contains values in rows 0 , 1, column 0.

this follows standard python conventions. @ results of these analogous expressions:

>>> = [0, 1, 2, 3, 4, 5] >>> a[4] 4 >>> a[4:5] [4]

as can see, 1 returns one item, while other returns a list containing 1 item. way python works, , numpy following convention, @ higher dimension. whenever pass slice rather individual item, list returned; true if there no items in list, either because end index low, or because starting index high:

>>> a[4:4] [] >>> a[6:6] []

so in situations, passing slice means "return sequence (along given dimension)," while passing integer means "return single item (along given dimension)."


Comments

Post a Comment

Popular posts from this blog

java.util.scanner - How to read and add only numbers to array from a text file -

i'm learning java , have question regarding reading file want read numbers file contains strings well. here example of file: 66.56 "3 java 3-43 5-42 2.1 1 and here coding: public class test { public static void main (string [] args){ if (0 < args.length) { file x = new file(args[0]); try{ scanner in = new scanner( new fileinputstream(x)); arraylist<double> test = new arraylist<>(); while(in.hasnext()){ if(in.hasnextdouble()){ double f=in.nextdouble(); test.add(f);} else {in.next();} } catch(ioexception e) { system.err.println("exception during reading: " + e); } } my problem add 66.56,2.1 , 1 doesn't add 3 after "3 or ignores 3-43 , 5-42 can tell me how skip strings , add doubles here? thanks all said 3 ie; "3, 3-43 , 4-42 strings either u read string , split , check number @ " , - or put in space between characters , integers. jvm after compilation tre...
Read more

rewrite - Trouble with Wordpress multiple custom querystrings -

i'm working on adding multiple querystring , doesn't seem work. i've found codes seems work others might i'm missing something. i want like: http://mydomain.com/board/?getyear=2013&getsometext2=sometext to http://mydomain.com/board/2013/sometext/ i added code below functions.php file. doesn't seem work should though. this works. echoing querystring gets both variable without problem. http://mydomain.com/board/2013/sometext/ but doesn't. tested querystring vis isset() seems nothing being set/get http://mydomain.com/board/2013/ function add_query_vars($vars) { $vars[] = "getyear"; $vars[] = "getsometext2"; return $vars; } add_filter('query_vars', 'add_query_vars'); function add_rewrite_rules($arules) { $anewrules = array('board/([^/]+)/([^/]+)/?$' => 'index.php?pagename=board&getyear=$matches[1]&getsometext2=$matches[2]'); $arules = $a...
Read more