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Population Density #26

Closed mtango99 closed 3 years ago

mtango99 commented 3 years ago

Is anyone else's population densities in the millions...?

majacannavo commented 3 years ago

I don't think we actually need to include pop density on the map if that helps--I didn't end up calculating it.

vinfalardeau commented 3 years ago

I have a few catchment areas around NYC with populations in the millions, but otherwise it's mostly in the tens or hundreds of thousands, and I just tried doing density (population per sq. km) and actually got lower values... Did you extract just the rows of the attribute table with the maximum potential for each town? Because I was having a hard time with that earlier and that seems like something that could lead to much higher values (e.g. taking the sum of input weights for k times more rows).

I think Maja is right that we don't need density, but I imagine if you've got densities in the millions then the raw populations must be even higher? Unless the areal units are a lot larger than square kilometers

mtango99 commented 3 years ago

Yeah I think maybe my area units are really weird... they must be lower than 1 for each catchment which it’s definitely not because they’re measured in meters. I did “SumInputWeight”/area($geometry) It does say somewhere on one of Joe’s pages we need pop density but he didn’t include it in his example so I’m not sure

From: vinfalardeau notifications@github.com Sent: Sunday, March 7, 2021 7:09:51 PM To: GIS4DEV/GIS4DEV.github.io GIS4DEV.github.io@noreply.github.com Cc: Tango, Maddie mtango@middlebury.edu; Author author@noreply.github.com Subject: Re: [GIS4DEV/GIS4DEV.github.io] Population Density (#26)

I have a few catchment areas around NYC with populations in the millions, but otherwise it's mostly in the tens or hundreds of thousands, and I just tried doing density (population per sq. km) and actually got lower values... Did you extract just the rows of the attribute table with the maximum potential for each town? Because I was having a hard time with that earlier and that seems like something that could lead to much higher values (e.g. taking the sum of input weights for k times more rows).

I think Maja is right that we don't need density, but I imagine if you've got densities in the millions then the raw populations must be even higher? Unless the areal units are a lot larger than square kilometers

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majacannavo commented 3 years ago

I think it might have gotten removed from the page--it says we needed four layers on our web map but now there are only three listed (and I think the fourth was pop density)

josephholler commented 3 years ago

Yes: I needed to simplify this a bit-- removed any static map design or population density.

Could area($geometry) be calculating in degrees2 ? If so, try reprojecting or using $area which can manage geodesic calculation in the units specified by the project's length/area calculation settings.

mtango99 commented 3 years ago

That was it! $area worked. Thanks

From: Joseph Holler notifications@github.com Sent: Sunday, March 7, 2021 8:19:24 PM To: GIS4DEV/GIS4DEV.github.io GIS4DEV.github.io@noreply.github.com Cc: Tango, Maddie mtango@middlebury.edu; Author author@noreply.github.com Subject: Re: [GIS4DEV/GIS4DEV.github.io] Population Density (#26)

Yes: I needed to simplify this a bit-- removed any static map design or population density.

Could area($geometry) be calculating in degrees2 ? If so, try reprojecting or using $area which can manage geodesic calculation in the units specified by the project's length/area calculation settings.

— You are receiving this because you authored the thread. Reply to this email directly, view it on GitHubhttps://github.com/GIS4DEV/GIS4DEV.github.io/issues/26#issuecomment-792399278, or unsubscribehttps://github.com/notifications/unsubscribe-auth/AOZTNMMW7MWA46GF3W3E4E3TCQQZZANCNFSM4YYL5UHA.