Since we're tracking our bird sightings and

conservation status, let's write a query to see how many sightings

have been reported of birds that are at risk of becoming endangered.

Make sure you've got your birds list and your C# REPL.

First, let's check out the different conservation statuses the birds have.

for statuses equals birds.Select,

b goes to b.Conservationstatus and

then I call Distinct so I remove the duplicates statuses.

So we've got least concerned, endangered, vulnerable,

near threatened and critically endangered.

We only want to concern ourselves with the endangered statuses So,

why don't we take out least concerned and near threatened.

Let's reassign it the same variable but without those statuses.

So statuses = statuses.Where

s goes to s is not equal to

"LeastConcern" and

s is not equal to "NearThreatened".

Okay, so now our statuses has only what we want to deal with.

We'll need to access the sightings of birds and

then only get those that are in our list of statuses.

I bet there are a lot of ways we can achieve this.

The first thing I think of when I've got two different collections is a join

we can join our list of birds to the status as a variable

then we'll only get the birds that have that status.

FarendangeredSightings equals

start with birds.join statuses

I'll do a new line here.

So our outer key would be birds b goes to

b.ConservationStatus facial and

then our inner key selector From our statuses list,

s => s, cuz it's just strings.

All right, now for our result.

I'll just use the two input parameters (b,

s) => I'm gonna create a anonymous type here

new status equals s and

birds equals b, okay.

Let's see what that gives us.

EndangeredSightings.

We've got lists of birds, but now we need the sightings.

Well we could actually put in sightings

inside our anonymous objects to get the sightings instead of the birds.

So I'm gonna use my Up arrow key to get most of the query back so I can reuse it.

B goes to B dot conservation status.

Then S goes to S but here I'm going to do B S

goes to new we'll keep the statuses.

We like statuses.

Equals s but this time I'm gonna say Sightings

equals b.Sightings.

Okay, let see what that gives us, endangered sightings.

So we've got one element for each bird.

We need to group them and then get a total count for each status.

So let's group by status.

So var endangered sightings.

Actually how about I clear the console?

Okay, and then I'm gonna use my up arrow key again to get my history.

var endangeredSightings = birds.Join(statuses,.

Yep, looks good.

b => b.ConservationStatus and then.

S goes to S.

But then I'll do b, s goes to

new status.

Actually we're gonna do the same thing.

I coulda used my arrow key.

But that's okay.

Status = s and then Sightings

= b.Sightings then I'm

going to call .GroupBy

b goes to b.Status because,

Our anonymous type here, the property is status so we're gonna group by that.

Okay, and endangeredSightings.

All right.

Well it looks like our statuses are there, and our sightings Okay we do have

a group it's a little hard to see like this so let's do that same query again.

I'm gonna clear the console.

All right, endangeredSightings b goes to

b.ConservationStatus s goes to s then that but

then, instead of returning sightings,

let's do a select here .Select b goes to new.

Then we'll do Status = b.Key

which should be our status, right, because we just did the GroupBy Status.

Next it's key and then the Sightings

is going to be equal to the b.Sum and

then s goes to s.Sightings .Count.

So we're gonna get the sum of the count of the sightings for each grouping by status.

Then we need to curly brace to end our anonymous type and

then close the Select method and Okay,

let's see what we get now endangeredsightings.

All right, great.

We've got 14 sightings of endangered birds.

29 are vulnerable and 12 of critically endangered.

Looks like I misspelled endangered.

[LAUGH]