How to convert Array Objects into another using LINQ?

Question

I have a List of Anonymous objects containing following fields in C# derived from a LINQ query.

{ 
String category
decimal Jan
decimal Feb
decimal Mar
decimal Apr
decimal May
decimal Jun
decimal Jul
decimal Aug
decimal Sep
decimal Oct
decimal Nov
decimal Dec
}

how could I create a list of Objects having one field for each value of category ( so essentially 12 objects one object for each month( jan, feb, march etc.).

ExpectedResult {
string Month, 
decimal category1,
decimal category2,
decimal category3,
...
decimal categoryN
}

So result would have 12 objects of ExpectedResult. Not knowing how many categories/is a problem. Any quick suggestion would be helpful.

So the new object would look like var Jan = { Cat1Name = 1.3, Cat2Name = 15.5, Cat3Name = 90.6, ... }? What to do if the category name is not a valid C# identifier? — mellamokb
– mellamokb, Commented Apr 4, 2012 at 21:22
I would like to a var newItem = new { Month = Jan, Cat1Name = 1.3, cat2Name= 13.5...} — Kishor Patil
– Kishor Patil, Commented Apr 4, 2012 at 21:25
Since the field names are going to be dynamically generated, it will be difficult to work with this anonymous object. What is the goal you are trying to accomplish? How will these new objects be used? — mellamokb
– mellamokb, Commented Apr 4, 2012 at 21:29
If you want to project the result into types with properties having the names the values from Category, then @mellamokb is right — Adrian Iftode
– Adrian Iftode, Commented Apr 4, 2012 at 21:33
I would be converting the list to Json and pass it to javascript. — Kishor Patil
– Kishor Patil, Commented Apr 4, 2012 at 21:33

KeithS · Accepted Answer · 2012-04-04 21:50:33Z

2

You can try a SelectMany() method:

anonymousList.SelectMany(x=>new[]{
                                    new {Cat=category, Month="Jan", Val=Jan}, 
                                    new {Cat=category, Month="Feb", Val=Feb}, 
                                    ... , 
                                    new {Cat=category, Month="Dec", Val=Dec}
                                 });

For each of your source anonymous objects, this query will produce an array of 12 new anonymous objects, and then those arrays (as Enumerables) will be concatenated into one large collection.

Just to avoid comparing strings later on, consider using an Enum for the months of the year (unfortunately .NET doesn't have one built-in):

public enum Month
{
   January = 1,
   February = 2,
   ...
   December = 12
}

...

anonymousList.SelectMany(x=>new[]{
                                    new {Cat=category, Month=Month.January, Val=Jan}, 
                                    new {Cat=category, Month=Month.February, Val=Feb}, 
                                    ... , 
                                    new {Cat=category, Month=Month.December, Val=Dec}
                                 });

answered Apr 4, 2012 at 21:50

KeithS

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2 Comments

Adrian Iftode Over a year ago

This is not what the OP needs. He wants several anonymous classes of the following definition: { public string Month, public decimal Category1, public decimal Category2, public decimal Category3 } where Category1..n are values from the previous query. Which is not possible (excluding emitting IL code :))

Kishor Patil Over a year ago

@KeithS, tried your solution. It creates multiple entries. What we expect is consolidated result of 12 records - one for each month. Unfortunately, I am not able to Group them once you create new category.

aKzenT · Accepted Answer · 2012-04-04 22:31:53Z

0

Starting from KeithS answer you could group this by months:

var results = from x in KeithsAnswer
              group x by x.Month into g
              select new { Month = g.Key, CategoryValues = g.Select(c => new { c.Month, c.Val }).ToArray()};

You can pass this directly to the client to process there or if you really need the form you specified above, you can implement your own JavaScriptConverter or use a dynamic/ExpandoObject to store the values as properties.

answered Apr 4, 2012 at 22:31

aKzenT

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