Flip associative array and store new values in subarrays to prevent losing duplicated values
$grouped = array(); foreach ($input as $choice => $group) { $grouped[$group][] = $choice; } var_dump($grouped);
arrays
Why can’t I assign an array variable directly to another array variable with the ‘=’ operator?
Because when you have a function call like this UCSDStudent( char name[] ) only the adress of the array name is copied instead of the whole array. It is a C\C++ feature. Furthermore the name defined as char name [20] is not a modifiable lvalue. Regarding strcpy: it will bring undefined behaivour as if your … Read more
In an assignment A(:) = B, the number of elements in A and B must be the same
This error comes because you are trying to fill a variable chunk with more (or less) values than its size. In other words, you have a statement A(:)=B on where size(A(:)) is different to size(B). In the example in the question, rand(3) returns a 3×3 matrix, however, output(ii) is just a single value (even if … Read more
Normalize Array methods and return values
I don’t think it is really inconsistent. Yes, they might be a little confusing as JavaScript arrays do all the things for which other languages have separate structures (list, queue, stack, …), but their definition is quite consistent across languages. You can easily group them in those categories you already described: list methods: push/unshift return … Read more
Why is Numpy much faster at creating a Zero array compared to replacing the values of an existing array with zeros?
The reason is that the array is not filled in memory on mainstream operating systems (Windows, Linux and MaxOS). Numpy allocates a zero-filled array by requesting to the operating systems (OS) a zero-filled area in virtual memory. This area is not directly mapping in physical RAM. The mapping and zero-initialization is generally done lazily by … Read more
Accessing JSON array after json_decode/multidimensional array
Assuming that you’ve chosen to decode the JSON as a multi-dimensional array, rather than as objects: foreach ($results as $tweet) { $user = $tweet[“from-user”]; $text = $tweet[“text”]; $entities = $tweet[“enities”]; $urls = $entities[“urls”]; foreach ($urls as $url) { echo $url[“expanded_url”]; } } et cetera
Numpy sub-array assignment with advanced, mixed indexing
Looks like there are some errors in copying your code to question. But I suspect there’s a known problem with indexing: In [73]: a=np.zeros((2,3,4)); b=np.ones((3,4)); I=np.array([0,1]) Make I 2 elements. Indexing b gives the expected (3,2) shape. 3 rows from the slice, 2 columns from I indexing In [74]: b[:,I].shape Out[74]: (3, 2) But with … Read more
What is the equivalent of Presto UNNEST function in Hive
Use lateral view [outer] explode. A lateral view first applies the UDTF to each row of base table and then joins resulting output rows to the input rows to form a virtual table having the supplied table alias. This is example from Presto migration from Hive docs: SELECT student, score FROM tests LATERAL VIEW explode(scores) … Read more
What expressions are allowed as the array length N in [_; N]?
As of Rust 1.24.1, the array length basically needs to either be a numeric literal or a “regular” constant that is a usize. There’s a small amount of constant evaluation that exists today, but it’s more-or-less limited to basic math. a perfectly valid expression in other contexts, just not as a length parameter to an … Read more
Lodash create collection from duplicate object keys
Use _.groupBy and then _.map the resulting object to an array of objects. var newOutput = _(output) .groupBy(‘article’) .map(function(v, k){ return { article: k, titles: _.map(v, ‘title’) } }) .value(); var output = [{“article”:”BlahBlah”,”title”:”Another blah”},{“article”:”BlahBlah”,”title”:”Return of the blah”},{“article”:”BlahBlah2″,”title”:”The blah strikes back”},{“article”:”BlahBlah2″,”title”:”The blahfather”}]; let newOutput = _(output) .groupBy(‘article’) .map(function(v, k){ return { article: k, titles: _.map(v, … Read more