You can use: df.loc[0, ‘diff’] = df.loc[0, ‘val’] * 0.4 for i in range(1, len(df)): df.loc[i, ‘diff’] = (df.loc[i, ‘val’] – df.loc[i-1, ‘diff’]) * 0.4 + df.loc[i-1, ‘diff’] print (df) id_ val diff 0 11111 12 4.8000 1 12003 22 11.6800 2 88763 19 14.6080 3 43721 77 39.5648 The iterative nature of the calculation … Read more
Something like this: function makeNonNestedRecursive(array &$out, $key, array $in){ foreach($in as $k=>$v){ if(is_array($v)){ makeNonNestedRecursive($out, $key . $k . ‘_’, $v); }else{ $out[$key . $k] = $v; } } } function makeNonNested(array $in){ $out = array(); makeNonNestedRecursive($out, ”, $in); return $out; } // Example $fooCompressed = makeNonNested($foo);
Your code is just missing a loop to inspect each child of a node in the child array. This recursive function will return the label property of a node or undefined if label not present in tree: const search = (tree, target) => { if (tree.id === target) { return tree.label; } for (const child … Read more
The problem is an incompatibility, (which I’ll show how to resolve) between unique closure types, how generics are instantiated when Rust is compiled, and a recursive use of the closure. fn map_nodes<F, R>(f: F, n: &Node) -> Vec<R> where F: Fn(&Node) -> R, Each recursive call instantiates a new version of this function, with a … Read more
why does recursion cause stackoverflow so much more than loops do Because each recursive call uses some space on the stack. If your recursion is too deep, then it will result in StackOverflow, depending upon the maximum allowed depth in the stack. When using recursion, you should be very careful and make sure that you … Read more
You can’t do recursive queries with HQL. See this. And as stated there it is not even standard SQL. You have two options: write a vendor-specific recursive native SQL query make multiple queries. For example: // obtain the first node using your query while (currentNode.parent != null) { Query q = //create the query q.setParameter(“id”, … Read more
Although you often see the following as an example of converting factorial to tail-call: int factorial(int n, int acc=1) { if (n <= 1) return acc; else return factorial(n-1, n*acc); } it’s not quite correct, since it requires multiplication to be both associative and commutative. (Multiplication is associative and commutative, but the above doesn’t serve … Read more
You could use reduce like this: const keyify = (obj, prefix = ”) => Object.keys(obj).reduce((res, el) => { if( Array.isArray(obj[el]) ) { return res; } else if( typeof obj[el] === ‘object’ && obj[el] !== null ) { return […res, …keyify(obj[el], prefix + el + ‘.’)]; } return […res, prefix + el]; }, []); const input … Read more
There are two basic methods for doing this: adjacency lists and nested lists. Take a look at Managing Hierarchical Data in MySQL. What you have is an adjacency list. No there isn’t a way of recursively grabbing all descendants with a single SQL statement. If possible, just grab them all and map them all in … Read more
You can rotate a list in place in Python by using a deque: >>> from collections import deque >>> d=deque([1,2,3,4,5]) >>> d deque([1, 2, 3, 4, 5]) >>> d.rotate(2) >>> d deque([4, 5, 1, 2, 3]) >>> d.rotate(-2) >>> d deque([1, 2, 3, 4, 5]) Or with list slices: >>> li=[1,2,3,4,5] >>> li[2:]+li[:2] [3, 4, … Read more