metric into grp select new { key = grp. Key, cnt = grp. Count()}; This result gave me an ordered set of records with 'metrics' and the number of users associated with each.
After calling GroupBy
, you get a series of groups IEnumerable<Grouping>
, where each Grouping itself exposes the Key
used to create the group and also is an IEnumerable<T>
of whatever items are in your original data set. You just have to call Count()
on that Grouping to get the subtotal.
foreach(var line in data.GroupBy(info => info.metric)
.Select(group => new {
Metric = group.Key,
Count = group.Count()
})
.OrderBy(x => x.Metric))
{
Console.WriteLine("{0} {1}", line.Metric, line.Count);
}
I'm assuming you already have a list/array of some class
that looks like
class UserInfo {
string name;
int metric;
..etc..
}
...
List<UserInfo> data = ..... ;
When you do data.GroupBy(x => x.metric)
, it means "for each element x
in the IEnumerable defined by data
, calculate it's .metric
, then group all the elements with the same metric into a Grouping
and return an IEnumerable
of all the resulting groups. Given your example data set of
<DATA> | Grouping Key (x=>x.metric) |
joe 1 01/01/2011 5 | 1
jane 0 01/02/2011 9 | 0
john 2 01/03/2011 0 | 2
jim 3 01/04/2011 1 | 3
jean 1 01/05/2011 3 | 1
jill 2 01/06/2011 5 | 2
jeb 0 01/07/2011 3 | 0
jenn 0 01/08/2011 7 | 0
it would result in the following result after the groupby:
(Group 1): [joe 1 01/01/2011 5, jean 1 01/05/2011 3]
(Group 0): [jane 0 01/02/2011 9, jeb 0 01/07/2011 3, jenn 0 01/08/2011 7]
(Group 2): [john 2 01/03/2011 0, jill 2 01/06/2011 5]
(Group 3): [jim 3 01/04/2011 1]
Assuming userInfoList
is a List<UserInfo>
:
var groups = userInfoList.GroupBy(n => n.metric)
.Select(n => new
{
MetricName = n.Key,
MetricCount = n.Count()
})
.OrderBy(n => n.MetricName);
The lambda function for GroupBy()
, n => n.metric
means that it will get field metric
from every UserInfo
object encountered. The type of n
is depending on the context, in the first occurrence its of type UserInfo
, because the list contains UserInfo
objects. In the second occurrence n
is of type Grouping
, because now its a list of Grouping
objects.
Grouping
s have extension methods like .Count()
, .Key()
and pretty much anything else you would expect. Just as you would check .Length
on a string
, you can check .Count()
on a group.
userInfos.GroupBy(userInfo => userInfo.metric)
.OrderBy(group => group.Key)
.Select(group => Tuple.Create(group.Key, group.Count()));
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