======= QGIS =======

First, let's get this over with and go with the basics.

=== Shape Files ===
What are shape files ? They are files that store polygons. An example of a shape is a triangle, which consists of 3 X,Y coordinates on a 2 dimensional plane. A square has 4, and so on. A state or a county can have hundreds of points. States like Colorado (basically a square)are much simpler compared to New York, New Jersey, etc.. or Wisconsin.

=== PUMA ===
The US census no longer provides information about counties. Instead they have come up with regions called PUMAs, which represent units of 100K people. In some counties that are huge (New York, Brooklyn) there are many PUMA regions in each county. In South Dakota, multiple counties are merged to form a single PUMA area. 

=== PUMA DATA ===
Where can I find this PUMA data ? I downloaded it from here: https://www2.census.gov/geo/tiger/TIGER2020/PUMA/

=== Shapefile Files ===
Since each shape file corresponds to a state, I created a directory for each state and placed the assorted zip files into those directories.

For example, file “tl_2020_34_puma10.zip” will go into directory /opt/qgis/puma_2020/NJ
I then proceeded to unzip each file in their respective directory.


===== Starting your Project =====
Menu --> Project --> New

==== Showing a street map ====
Menu --> Web --> Quick Map Services --> OSM --> OSM Standard

You can zoom in on an area by using the scroll wheel on your mouse

==== Adding files to your project ====
  * Menu --> Layer --> Data Source Manager
  * On the left hand menu, it should default to "Browser"
  * On the main panel, choose the directory where your data is located (ie. /opt/qgis)
  * For each state do:
    * Choose the file with the extension ".shp"
    * Double click the file

==== Assigning Colors to Areas ====

I want each state to have it's own color, and each region to be a gradient of that main color. 

We'll have 4 main map colors (<fc #ff0000>red</fc>/<fc #00ff00>green</fc>/<fc #4682b4>blue</fc>/<fc #ffa500>orangello</fc>)

  - In order for each PUMA region to have it’s own color, 
    - right click the layer 
    - Go to Properties --> Symbology
  - On the VERY UPPER drop down, choose "Categorized" 
  - The "Value" is a field that included in the file (a long story). Choose GEOID10
  - Click "Classify" to display all the GEOID10 values
  - For the "Color Ramp", choose a pre-installed theme (like "Reds)
  - In the file, choose a unique value that will identify each individual region 
    - (in this case, column PUMACE10)
  - In the “Color Ramp”, I chose “Randomize Colors”
  - Click the “Classify” button and all the values will appear next to it’s respective color.
  - Click “OK”

{{:census:qgis_assign_colors.png?600|}}