diff --git a/syllabus.doc b/syllabus.doc index 8073afa..c35408a 100644 Binary files a/syllabus.doc and b/syllabus.doc differ diff --git a/syllabus.pdf b/syllabus.pdf index bd4361e..cd819ee 100644 Binary files a/syllabus.pdf and b/syllabus.pdf differ diff --git a/week2.html b/week2.html index 8fed609..f770aa6 100644 --- a/week2.html +++ b/week2.html @@ -444,7 +444,7 @@ - + Geospatial data analysis in R @@ -1447,7 +1447,7 @@

Geospatial data analysis in R

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September 20, 2024

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September 23, 2024

Introduction to geospatial data

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Shapefiles

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  • Shapefiles are made up of at least four files: +
  • Shapefiles are made up of at least three files:
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    Let’s look at Northern Malawi

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    Let’s look at Northern Malawi

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    Types of features

    Let’s start with polygons

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    Imagine a rectangle, on a coordinate plane

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    All features are made of vertices

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    All features are made of vertices

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    One more example of polygons

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    One more example of polygons

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    One more example of polygons

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    Lines

    Lines example - “Primary” roads in India (2014)

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    One road




    Length of this line feature: 1619.93 (m)


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    Points

    Reading shapefiles in R

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    My go-to theme

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    My go-to theme

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    Other changes you can make

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    Other changes you can make

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    Give it a try with TAs (admin3) in Malawi (mw3.shp)

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    One more example - map from earlier

    What if we want to plot mw2, mw3, and mw4?

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    What if we want to plot mw2, mw3, and mw4?

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    The basic problem

    Preserve shape, give up area

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    Projections

    Meractor projection: preserves angular relationships

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    Azimuthal Equidistant projection

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    Mollweide Equal Area Cylindrical projection

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    Three families of projections

    Coordinate reference systems

    A common CRS: Universal Transverse Mercator (UTM)

    A common CRS: Universal Transverse Mercator (UTM)

    Projections with sf

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    What is the appropriate zone for Malawi?

    They look quite similar!

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    They look quite similar! Different coordinates

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    They look quite similar! Different coordinates

    Malawi is small. What about something larger?

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    Now it’s your turn!

    More practice

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    Returning to the files

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    diff --git a/week2.qmd b/week2.qmd index 33d0e69..1a7b25a 100644 --- a/week2.qmd +++ b/week2.qmd @@ -104,11 +104,12 @@ kdisgray <- "#A7A9AC" - Shapefiles are a common format for geospatial data - They are a form of `vector` data -- Shapefiles are made up of _at least_ four files: +- Shapefiles are made up of _at least_ three files: - `.shp` - the shape itself - `.shx` - the index - `.dbf` - the attributes - `.prj` - the projection + - This one is not technically necessary! But it's common to have. - What these all mean isn't important for now, just make sure they are there! Check the `week2files` folder on github. @@ -1619,6 +1620,25 @@ plot_grid(g1, g2) + - Plot them side by side using `cowplot` + + + +## Returning to the files + +- Shapefiles are made up of _at least_ four files: + - `.shp` - the shape itself + - The geometry + - `.shx` - the index + - The "index". You can actual recover the .shx file from the .shp file + - `.dbf` - the attributes + - The attributes for each features. Could be names, population values, etc. + - `.prj` - the projection + - The projection information, which we just discussed + +- There are often more files, but these are the main ones + - You **must** have the first three. The fourth is optional, but common. + +