2. Data Collection and
Data Manipulation
Data Collection
For my project I used different sources of
data:
* First, I needed a basic map of Vancouver containing
the several roads. It was necessary that the layer of the roads was
connected with an attribute table to simplify the identification of one
special road. I got the data from the Department
of Geography, which had a collection of the data
from the Canadian Census 1996.
(S drive: GIS-Data; Census; Canada 1996 CSD; Documentation; street
network and feature)
* Second, I needed the exact location of the various 'Starbucks'
in Vancouver. Therefore I used the 'Yellow Pages':
http://www.yellowpages.ca
and downloaded the data I need.
A great advantage of this web site is that you can search
for the data you need simply by typing in what you are looking for (e.g.
'Starbucks', 'Vancouver', 'B.C.') and furthermore, the address doesn't
only include the street and the number of the house, but there is also
a small map showing where the exact location is. This was a very important
and useful function for me, because I had to digitize every single 'Starbucks'
in Vancouver.
* Third, I needed social data of different districts of
Vancouver. At least, I chose Census Tracts as basic units. As mentioned
above, I got my data from the Canadian Census 1996. Because of the various
factors regarded by the Census data, I had to choose only a few of them,
which I regarded would be necessary for my further analysis.
I got data of the following categories:
- data regarding the population, the size of the Census
Tracts
- data regarding the different groups and variables
of income
- data regarding employment in various sectors and (un-)employment
- data regarding the total numbers of women and men
- data regarding the different groups of age
- data regarding the different groups of ethnic
- data regarding the the size of households
Data Manipulation
The data of the roads and the shape of Vancouver have
already been prepared as shapefiles. I opened them with ArcView Gis
3.2. The georeference system is NAD_1983_UTM_Zone_10N.
Because my project is limited on the area of Vancouver, I had
to edit the shape of the layers showing only the Census Tracts
of Vancouver.
I created a new layer called 'starbucks.shp' in which I digitized
the location of every single 'Starbucks'.
Another step was the projection of the layer with the Census
Tracts. The shapefile of the Census Tracts had another projection
than the shapefile of the roads. I wasn't
able to determine this projection, because the necessary function in ArcToolbox
told me that there is no information about this projection available. As
a result an overlapping of the two layers was not possible. With ArcToolbox
and the function Project Wizard (shapefile,
geodatabase) I projected the census_tracts.shp
as NAD_1983_UTM_Zone_10N. Now, it is possible
to open the different layers in the same view and to edit the census_tract.shp
showing only the Census Tracts of Vancouver.
The attribute table of census_tract.shp don't contain all the
data I needed. That data was stored as a *mdb-file. To modify and change
the data I opened them in ArcCatalog and exported the *mdb-file
as a *dbf-file. In a next step I opened the *dbf-file in Microsoft Excel.
There I manipulated the data in the way I needed them. After the manipulation
I opened the *dbf-file in ArcView GIS 3.2 again and joined this table with
the attribute table of the census_tract.shp. To make this operation permanent
I stored them as a shapefile.
In IDRISI32 I imported every single shapefile I needed using the
function 'shapeidr'. The imported layers were stored in vector format.
The layers showing the distribution of Starbucks and the roads had
to be in a vector format, because they show single objects and no continuous
surface. In a first step I connected the layer of the Census Tracts with
its attribute table. In a second step I converted the latter in a raster
format finally having a continuous surface. The disadvantage of that conversion
is that the connected attribute table gets lost.
At least I converted all the data as *avl-files and assigned
new maps showing the wanted criterion. I chose the operation 'reclass'
and designed categories for the criterion I thought would be useful.
As a result I had eight maps showing the strength of different
social factors. I combined them with the layer of the distribution of
'Starbucks' and stored them as *bmp-file. For making them suitable for
the web site I opened them in ADOBE Photoshop 5.0 LE and stored them
as a *jpg-file.
As explained in the following spatial analysis these maps showed
the relationship between the distribution of 'Starbucks' and one specific
social factor.
After all I had eight principles. In a next step I wanted to determine
the suitability of the areas in Vancouver related to those principles.
Where are areas, which are most suitable for 'Starbucks'? Are there 'Starbucks'
located or should there new ones initialized? Where is it not useful to
initialize new ones?
For this last step of my analysis I used a Multi-Criteria evaluation
in IDRISI32. I reclassified each category of each map with a value between
0 and 255. 255 meaning most suitable and 0 meaning least suitable. I chose
a Non-Boolean Standardization and weighted each factor
in relation to the others. This means that e.g.
one factor with a high suitability can compensate one factor with a low
suitability.
The following screenshot shows an exerpt of the weighting:
My final result is a map showing areas of Vancouver, which are most suitable,
suitable and less suitable for (further) locations of 'Starbucks'.
Having all my maps and analysis finished I designed this web site demonstrating
my results with Netscape Composer.