indexing

问题 Is there any way to find a position of a first character within a string in Bash under Mac OS X ? Something like: stringZ=abcABC123ABCabc # 6 echo `expr index "$stringZ" C12` # C position. as desribed in Advanced Bash-Scripting Guide Couple of gotchas: The official index function expr index $string $substring is not present in OS X (BSD) match Installing gnu match ( gmatch ) does not seem to be a portable solution in the realm of BSD systems Any ideas? 回答1: This is a horrible hack, and may

问题 I am trying to count elements in a table that has some elements indexed with strings. When I try to use the # operator, it just ignores string indexed ones. example: local myTab = {1,2,3} print(#myTab) will return 3 local myTab = {} myTab["hello"] = 100 print(#myTab) will return 0 mixing them, I tried local myTab = {1,2,3,nil,5,nil,7} print(#myTab) myTab["test"] = try print(#myTab) returned 7 and then 3, that is right because I read somewhere that the # operator stops when it finds a nil

问题 Is there any way to find a position of a first character within a string in Bash under Mac OS X ? Something like: stringZ=abcABC123ABCabc # 6 echo `expr index "$stringZ" C12` # C position. as desribed in Advanced Bash-Scripting Guide Couple of gotchas: The official index function expr index $string $substring is not present in OS X (BSD) match Installing gnu match ( gmatch ) does not seem to be a portable solution in the realm of BSD systems Any ideas? 回答1: This is a horrible hack, and may

问题 I have a large Postgres table where I want to partial index on 1 of the 2 columns indexed. Can I and how do I use a Postgres function in the where clause of a partial index and then have the select query utilize that partial index? Example Scenario First column is "magazine" and the second column is "volume" and the third column is "issue". All the magazines can have same "volume" and "issue" #'s but I want the index to only contain the two most recent volumes for that magazine. This is

问题 I have two string arrays each with three columns.I want to compare first two columns of both 2-d arrays(having 3 cols and 4000 rows). if they match then i need those matching values.But my code is not working.Here is a sample. array1=["1stcolumn...", "2ndColumn...", "3rdColumn..."] array2=[1stcolumn 2ndColumn 3rdColumn] if (array1[0]==array2[0] and array1[1]==array2[1]): array3.append('matches: {!r}'.format(array1)) print(array3) 回答1: EDIT if array1[:2] == array2[:2]: compares all items from

问题 I want to search a list for the occurence of a value (x) and return that value and a number, say 2, of the values above and below x in the index. Value x might appear in the list multiple time. Input in = ['a','b','c','d','x','e','f','g','h','i','x','j','k','l'] Output out = ['c','d','x','e','f','h','i','x','j','k'] Thanks for any help or suggestions 回答1: In [8]: lis = ['a','b','c','d','x','e','f','g','h','i','x','j','k','l'] #create a new list containing all the index positions of 'x' In [9]

问题 I have a project completed with Orchard CMS. The all functionalities are implemented through modules. Search module was also working till a few days ago, but suddenly it is stopped to working, "without any reason". The issue is that I can not rebuild/update indexes. When I run indexing, it will only index default list of fields (id, title, body, format, type, author, created, published, modified, culture) but my custom fields are not indexed. I tried everything but without any success. I

问题 I want to implement scatter and gather operations of Tensorflow or PyTorch in Numpy. I have been scratching my head for a while. Any pointers are greatly appreciated! PyTorch Scatter PyTorch Gather 回答1: The scatter method turned out to be way more work than I anticipated. I did not find any ready made function in NumPy for it. I'm sharing it here in the interest of anyone who may need to implement it with NumPy. (p.s. self is the destination or output of the method.) def scatter_numpy(self,

问题 I want to implement scatter and gather operations of Tensorflow or PyTorch in Numpy. I have been scratching my head for a while. Any pointers are greatly appreciated! PyTorch Scatter PyTorch Gather 回答1: The scatter method turned out to be way more work than I anticipated. I did not find any ready made function in NumPy for it. I'm sharing it here in the interest of anyone who may need to implement it with NumPy. (p.s. self is the destination or output of the method.) def scatter_numpy(self,

问题 In Ruby, if I had an array a = [1, 2, 3, 4, 5] and I wanted to get the sum of each element times its index I could do a.each.with_index.inject(0) {|s,(i,j)| s + i*j} Is there an idiomatic way to do the same thing in Rust? So far, I have a.into_iter().fold(0, |x, i| x + i) But that doesn't account for the index, and I can't really figure out a way to get it to account for the index. Is this possible and if so, how? 回答1: You can chain it with enumerate: fn main() { let a = [1, 2, 3, 4, 5]; let