Linq / C＃：从分组依据中选择和求和？

Question

I have a list like this:

City   Total
Sydney 11
Dublin 9
London 12
Dublin 3
London 9
Sydney 12

I first of all need to Group By City & Sum Total so I have

Sydney 23
London 21

Next I need to filter for those that entries where the total is > 20

\nSydney 23 \nLondon 21 \n

And what I finally need is the total of these entries, eg 44

I really want to do it in 1 single LINQ statement, possible?

Thx,

Answer 1

int cityTotals = cities
    .GroupBy(c => c.City)
    .Select(grp => new { City = grp.Key, Total = grp.Sum(c => c.Total) })
    .Where(c => c.Total > 20)
    .Sum(c => c.Total);

Answer 2

A couple of alternative approaches to Lee's:

int cityTotals = cities
    .GroupBy(c => c.City)
    .Select(grp => grp.Sum(c => c.Total))
    .Where(total => total > 20)
    .Sum();

or

int cityTotals = cities
    .GroupBy(c => c.City, (key, grp) => grp.Sum(x => x.Total))
    .Where(total => total > 20)
    .Sum();