CODEWITHSUNDEEP
c#linq
90abyss
90abyss

Reputation: 7347

First group a list acc to a custom rule and later sort the group based on another field

I'm new to linq so please forgive my ignorance.

I've a list which I need to group based on a certain condition.

Now, my list contains 2 fields -

1) Type 2) Severity

My types are:

a) VM b) SQL c) LoadBalancer

My severity can be:

a) sev1 b) sev2 c) sev3

I want to group the list based on the following strict order: (so first LoadBalancer stuff should show - later VM - and finally SQL ones)

1) LoadBalancer 2) VM 3) SQL

And once they are grouped, I want to sort them based on severity.

I'm able to group it using a non-defined grouping mechanism here:

from i in thelist 
group i by i.Type;

I was reading some material online and it looks like i will have to override equals and hash method.. I'm not sure how to do that? Or is there some better approach?

Thanks.

Upvotes: 0

Views: 58

Answers (2)

rsqLVo
rsqLVo

Reputation: 498

Since you did not specify what objects are on this list ("Now, my list contains 2 fields -" (?) ) I assumed it's (please tell me if anything is wrong):

class TestItem {
    public string type;
    public string severity;
}

And with a bit of LINQ 

var test = list
    .OrderBy(i =>
        i.type.StartsWith("S") ? 3 :
        i.type.StartsWith("V") ? 2 : 1)
    .ThenBy(i => i.severity);

I know it's a bit of a hack, but it works for this weird type of sorting.

For the input:

new TestItem("VM", "sev1"),
new TestItem("SQL", "sev2"),
new TestItem("Load", "sev1"),
new TestItem("VM", "sev2"),
new TestItem("SQL", "sev1"),
new TestItem("Load", "sev2"),
new TestItem("SQL", "sev3")

Output (properties):

"Load", "sev1"
"Load", "sev2"
"VM", "sev1"
"VM", "sev2"
"SQL", "sev1"
"SQL", "sev2"
"SQL", "sev3"

Upvotes: 1

James Curran
James Curran

Reputation: 103535

Sorting them by Severity and then grouping by Type should work, but, as far as I know, grouping isn't guaranteed to be stable, so who knows?

If it isn't, the next best thing to do would be to sort the objects as you pull them out of the groups to use them.

Upvotes: 0

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