Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>The proposed solutions suffer from the fact that they create intermediate collections or introduce variables which are not strictly necessary. For ultimately all you need to do is to keep track of the number of steps of an iteration. This can be done using memoizing. The resulting code might look like</p> <pre><code>myIterable map (doIndexed(someFunction)) </code></pre> <p>The <code>doIndexed</code>-Function wraps the interior function which receives both an index an the elements of <code>myIterable</code>. This might be familiar to you from JavaScript.</p> <p>Here is a way to achieve this purpose. Consider the following utility:</p> <pre><code>object TraversableUtil { class IndexMemoizingFunction[A, B](f: (Int, A) =&gt; B) extends Function1[A, B] { private var index = 0 override def apply(a: A): B = { val ret = f(index, a) index += 1 ret } } def doIndexed[A, B](f: (Int, A) =&gt; B): A =&gt; B = { new IndexMemoizingFunction(f) } } </code></pre> <p>This is already all you need. You can apply this for instance as follows:</p> <pre><code>import TraversableUtil._ List('a','b','c').map(doIndexed((i, char) =&gt; char + i)) </code></pre> <p>which results in the list</p> <pre><code>List(97, 99, 101) </code></pre> <p>This way, you can use the usual Traversable-functions at the expense of wrapping your effective function. The overhead is the creation of the memoizing object and the counter therein. Otherwise this solution is as good (or bad) in terms of memory or performance as using unindexed <code>map</code>. Enjoy!</p>
    singulars
    1. This table or related slice is empty.
    1. POHow can I use map and receive an index as well in Scala?
      singulars
      1. PTQuestion
    1. PTAnswer
    1. This table or related slice is empty.
    1. USMatt Brasen
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COThis is a very elegant solution to the problem. +1 for not creating a temporary collection. Won't work in a parallel collection, but still a very nice solution.
      singulars
      1. PO
      1. USfbl
    2. COIf you don't want to create a temporary collection, just use `coll.view.zipWithIndex` instead of `coll.zipWithIndex`
      singulars
      1. PO
      1. UStsuna
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload