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Maps and projections in Geopandas

No map is perfect. It's impossible to accurately represent a three dimensional object (planet Earth) in two dimensions (a map on paper or on a screen). Every map representation comes with physical and political biases. That's why it is important to have a range of options for map projections, to be able to identify the map with the least problematic biases.

I went through a lot of pain trying to change the map projection in a report I was creating using Geopandas. The official documentation makes it look like there are only two projections, WGS84 and Mercator. It does start by saying that any reputable data source should have projection information included -- but that doesn't account for all the times we come across messy data sources, or that we are generating our own data sets.

There are actually many projections available for Geopandas to use. I found this out by reading this guide which uses the Robinson projections and got me thinking that there must be others. But what are the others? They are included in Basemap's documentation, but as it turns out, they can also be used in Geopandas.

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Python and GeoPandas

Fri 22 June 2018 | tags: python | pandas |

I recently worked on a report documenting instructor and workshop activities for The Carpentries. Much of it was built using Pandas, a tool I am relatively familiar with. I also included some geospatial visualizations, using GeoPandas for the first time.

The Python GeoPandas library works much like Pandas, but for …
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Using grep
Sun 19 November 2017 | tags: shell | bash |

grep is a bash program that searches files for lines containing a match to a given pattern.

Without any special tricks, it's used like this. This will search for the pattern string inside the file file.txt. Each line that matches is displayed entirely.
```
grep 'string' file.txt
```
This can …
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ssh and Raspberry Pi

Thu 22 June 2017 | tags: raspberrypi |

Many years ago I got an early version of the Raspberry Pi. I fiddled with it a bit but didn't do much with it. A few months ago I decided to buy a newer version to have a mini computer I could use for a specific web scraping project I …
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Subtotals and Grouping with Pandas

Wed 01 March 2017 | tags: python | pandas |

For a long time, I've had this hobby project exploring Philadelphia City Council election data. I've learned no agency has this data collected or maintained in a consistent, normalized manner. From election to election, vote counts are presented in different ways (as explored in this blog post), candidate names are …
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Looping through Python command line arguments
Mon 20 February 2017 | tags: shell | bash | python |

I have a Python script that does some image manipulation and outputs a new file. From the command line, it takes two arguments, the old file and new file:
```
python image_converter.py oldfile.jpg newfile.jpg
```
I wanted to run this over a bunch of files, and used this bash …
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Making files by the batch
Mon 13 February 2017 | tags: shell | bash |

I had a list of names and I wanted to create an empty file with each of those names.

First I saved my list of names to a file with the .md extension since they were all going to be markdown files.

names.txt
```
barack.md
joe.md
hillary.md …
```
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Stashing revisions in Git

Tue 22 November 2016 | tags: git |

Sometimes I'll be working on a project, having moved along a few steps from my last commit, only to remember there was something else I wnated to do before the point I'm at now. Since the point I'm at now isn't really ready for a commit, I don't want to …
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Django Databases and Date Ranges

Sun 13 November 2016 | tags: python | django |

I'm continuing to work on my project analyzing data about Philadelphia City Council - elections, demographics, terms of service, etc., even as heartbroken and terrified I am about the recent Presidential election. A very crude version of this project is here. A big thing that this never did was to look …
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Jupyter Notebook and the Django shell

Fri 04 November 2016 | tags: python | django |

I've been working on a project analyzing data about Philadelphia City Council - elections, demographics, terms of service, etc. A very crude version of this project is here. I want to make this more robust, and a big part of doing so includes playing with code. One of my favorite ways …
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