Databases
StackOverflow2013
Postsdbo
POCalculate average with linq without grouping
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POCalculate average with linq without grouping
    primarykey
    data
    text
    <p>I have a datatable, wich contains a several columns. I want to calculate the average of these with linq, without grouping: I tried this:</p> <pre><code>dtPointCollFb.GroupBy(r =&gt; 1).Select(r =&gt; new { Plus100 = r.Average(item =&gt; item.PLUS100), Plus50 = r.Average(item =&gt; item.PLUS50), Plus10 = r.Average(item =&gt; item.PLUS10), Plus5 = r.Average(item =&gt; item.PLUS5), Plus1 = r.Average(item =&gt; item.PLUS1), NULLA = r.Average(item =&gt; item.NULLA) }).ToList() </code></pre> <p>This works perfectly, when I calculate Sum, but with average produce the first record values, not all records' average. I think this is unnecessary: .GroupBy(r => 1) because I'm grouping with constant.</p> <p>But without this i can't use average just for the whole query, and only for one column:</p> <pre><code>dtPointCollFb.Average(r =&gt; r.PLUS100) </code></pre> <p>So can someone produce a simple best practice solution? If it's possible with method syntax, not query.</p> <p>I want something like this:</p> <pre><code>dtPointCollFb.GroupBy(r =&gt; 0).Select(r =&gt; new { Plus100 = r.Sum(item =&gt; item.PLUS100) / dtPointCollFb.Rows.Count, Plus50 = r.Sum(item =&gt; item.PLUS50) / dtPointCollFb.Rows.Count, Plus10 = r.Sum(item =&gt; item.PLUS10) / dtPointCollFb.Rows.Count, Plus5 = r.Sum(item =&gt; item.PLUS5) / dtPointCollFb.Rows.Count, Plus1 = r.Sum(item =&gt; item.PLUS1) / dtPointCollFb.Rows.Count, NULLA = r.Sum(item =&gt; item.NULLA) / dtPointCollFb.Rows.Count }).ToList() </code></pre> <p>but with simpler and cleaner way. This produce the average correctly.</p>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USspeti43
    1. USspeti43
    plurals
    1. PL
      singulars
      1. LTLinked
    2. PL
      singulars
      1. LTDuplicate
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POCalculate average with linq without grouping
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POCalculate average with linq without grouping
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. POCalculate average with linq without grouping
      1. This table or related slice is empty.
      1. VTUpMod
    1. CONot the same, but there is a suggestion to calculate the averages separately.
      singulars
      1. POCalculate average with linq without grouping
      1. USspeti43
    2. COJust for the record, the `GroupBy` construct is, I believe, intended to force all the averages to be computed on a single round-trip to the database.
      singulars
      1. POCalculate average with linq without grouping
      1. USRawling
    3. COYes, you are correct, it would be the best way, because I transport a lot of data from the sql server. This pattern was designed to make multiple aggregation on the webserver with linq. I calculate different things from the same data collection. I could do it in 5 different sql query. I don't know, maybe it would be better.
      singulars
      1. POCalculate average with linq without grouping
      1. USspeti43
 

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