Gothos

ESRI has just released another service pack for ArcGIS - Service Pack 5, which fixes a number of bugs and adds some additional functionality.

I received an email floating around the Maps-L listserve the other day with an announcement about a website that had African GIS data. Since free, global GIS data can be hard to find, particularly for Africa, I thought I’d re-announce it here.

The Southern African Human-development Information Management Network (SAHIMS) is a UN affiliated organization that provides humanitarian and disaster relief for countries in southern Africa. They have a pretty comprehensive collection of GIS data on their site: http://www.sahims.net. The default GIS page provides layers that cover the entire region, plus some layers for Tanzania (which is technically outside the region). But you can use the menu on the left of the page to navigate to country-specific data for: Angola, Botswana, Lesotho, Madagascar, Malawi, Mozambique, Namibia, Swaziland, Zambia, and Zimbabwe. There doesn’t appear to be any data for South Africa.

The layers are in shapefile format and include administrative boundaries (including sub-national boundaries), transportation, hydrological features, climate, food, and disaster related layers. The availability and details of each layer vary by country.

I downloaded a few of the layers, and many were missing spatial reference information. However they do provide decent metadata on their site, and you can use it to define the coordinate and projection system for each layer.

I attended the first of the three workshops held at Baruch College as part of the New York Census Research Data Center’s 2nd Annual Workshop series. The NYCRDC provides confidential census microdata to researchers at secure facilities at Baruch and Cornell.

This year’s theme is census geography and mapping, and there were a number of great presentations that covered census geography from the global down to the block level. My personal favorite was a presentation that illustrated the composition and evolution of census tracts - using Legos! Not the real ones mind you, but digital photos of Legos that were enhanced and tied together with Flash in a Powerpoint presentation.

I have provided a link to the 2nd Annual Workshop page before - but there it is again. Powerpoints, and perhaps video footage, of the presentations should be posted there relatively soon.

I also gave a promo to the hands-on GIS workshop that I’ll be doing as part of the second workshop of the series. Two weeks to go, and I still have a lot to do…

I’ve been preparing a GIS workshop for the New York Census Research Data Center’s 2nd Annual Workshop series, and have dug up some useful tips as I’ve assembled my materials. Here’s one of them:

I have a data table from the Census Bureau’s 2006 Annual Community Survey (ACS) in Excel which contains some data for Metropolitan and Micropolitan Areas. Now, I have a shapefile of Metropolitan Areas that I would like to join this data table to, but I would like to get rid of the records for the Micropolitan Areas in the data table. Unfortunately, the data table does not have a field that indicates whether an area is a Metro or Micro. Instead, this information is embedded in the name field, like “Akron, OH Metro Area” which means there is no way to sort the table to weed out the Micro Areas.

COUNTIF function to the rescue! I inserted a new column and typed in the formula:

=COUNTIF(D3, “*Metro*”)

If the formula sees the word Metro anywhere in the GEO_NAME, it counts it as a one in the new column, otherwise it counts it as zero (by default, the zeros will be the Micro areas). Copied and pasted the formula all the way down, then copied and pasted the formula column over top of itself using Paste Special (to replace the formulas with the actual values), and voila! Sorted by this column, and deleted all the records with a zero in the field (the Micro areas).

I’ve done something like this before in Microsoft Access using LIKE, but Excel doesn’t include this function. I knew about COUNTIF but didn’t connect the dots. I discovered I could apply it after stumbling across this useful post at Daily Dose of Excel.

Lastly, before you can bring this table into GIS, you have to delete that second header row (you can only have one column heading - the rest of the rows are assumed to be data). While the codes in the first row are cryptic, they are concise. The headings in the second row are too long and contain spaces, which will cause problems when you import the table into GIS.

NOTE - If you’re using Open Office’s Calc instead of Excel, and you have enabled regular expressions under the Tools - Options - OpenOffice.org Calc - Calculate menu, the same function would look like this:

=COUNTIF(D3;”.*Metro.*”)

Welcome to my little world of Gothos! Here, I will share my experiences, tips, musings, knowledge, mistakes, opinions, and thoughts as a geography / GIS librarian. We’ll cover data sources, data processing, map making, resources, and more. I’ll also post relevant announcements for the local GIS community at CUNY and beyond. Where possible, I’ll also share some of my work: maps, reference guides, and datasets. See the About page for additional info.