# Downtown Homelessness Source Package

Source files for San Diego Downtown homeless sleeper counts

sandiegodata.org-downtown_homeless-source-6

## Documentation

This dataset provides geographic locations for homeless sleepers in Downtown San Diego, as counted by enumerators from the Downtown San Diego Partnership. These counts have been done monthly since 2012, and this dataset provides counts since 2014.

This is the source package, use to generate analysis packages. Analysts should probably use one of the analysis packages. See the Data Library’s Homelessness Collection for all of the available datasets.

The count is done on paper maps with handwritten count marks. The San Diego Regional Data Library’s Downton Homelessness project converted these scanned count maps using a web based image annotation tool, VIA. These data are extracted from the JSON output from VIA.

This package has two top level files, and four predecessor files. The top level files are:

• counts. One record for each handwritten count marking on a map.
• files. One record for each of the scanned, handmarked maps.

The predecessor files are:

• raw_file_annotations. File annotations extracted from the VIA output.
• raw_count_annotations. Count annotations extracted from the VIA output.
• raw_gcp. Ground control point annotations ( street intersections ) extracted from VIA.
• gcp_transforms. Ground control points, in both image and geographic coordinates, with an affine transformation matrix to convert between them.
• intersections. Geographic positions and names of the street intersections used as ground control points.

## Caveats

Because this data is extracted, manually, from manually recorded maps, there are a lot of quality issues.

### Missing Months

Because of conversion errors and some complications with the source maps, there are several months of data that are excluded from this dataset

• August 2014. In the original datasets, August 2014 was a duplicate of September 2014.
• September 2014. Comfusion related to the duplication of September and August resulted in September being incompletely processed.
• June 2015. All of the map images for this month were blank. An alternate source PDF exists that is not blank, but this file was not used.

### Not Using Ocupancy Multipliers

Since about 2017, HUD has instructed point-in-time homeless counts to multiply the counts of sleepers in structures and vehicles by factors to account for people who may be obsured and not directly countable. From April 2017 on, Downtown San Diego Partnership has been using these factors.

However, this dataset does not use the occupancy factors, to allow analysts to apply these factors consistently across all months of data. As a result, the counts from this dataset diverge from the official counts after March 2017.

### Other Issues

• The total_count often does not match the sum of counts on the map. These sums were made by hand, by the enumerator who made the counts, so there are occasional arithmetic errors.
• There are many instances of missing values for rain or temp
• Some dates include the day of the month, but many don’t These dates have a day of month of 1.
• Date day of month is generally unreliable. Only the year and month are reliable, except for files noted above.
• The neighborhood value is based on the map names, so in some months the East Village neighborhood is separated into east_village and east_village_south

### Comparison to Official Published Counts

This plot shows, per month, the offical published counts from San Diego Downtown Partnership versus the total from this dataset. Note the descrepancies dues to issues noted above, including missing months, minor differences in some months, and the divergence after March 2017 due to occupancy multiplers.

## Versions

1. Initial Release
2. Remap some neighborhoods
3. Map null neighborhood name ( ” ) to Gaslamp
4. Fixed missing dates in Columbia, 2016, incorrect dates in Marina 2016, and other errors
5. Excluded several months with quality problems, improved documentation
6. Added column for source file, removed duplicated data form marina, 2016

## Packages

### Accessing Packages in Metapack

import metapack as mp
# ZIP Package
pkg = mp.open_package('http://library.metatab.org/sandiegodata.org-downtown_homeless-source-6.zip')
# CSV Package
pkg = mp.open_package('http://library.metatab.org/sandiegodata.org-downtown_homeless-source-6.csv')

resource = pkg.resource('resource_name') # Get a resource
df = resource.dataframe() # Create a pandas Dataframe
gdf = resource.geoframe() # Create a GeoPandas GeoDataFrame


## Data Dictionary

counts | files | raw_file_annotations | gcp_transforms | raw_gcp | raw_count_annotations | intersections

### counts

Column NameData TypeDescription
neighborhoodstringNeighborhood name
datedateDate of the count, or the first of the month if the day of the date isn’t specified.
countintegerNumber of sleepers counted in the observation
typestring“Individual”, “Structure” or “Vehicle”
xnumberGeographic X position, EPSG:2230, California State Plane 6
ynumberGeographic Y position, EPSG:2230, California State Plane 6

### files

Column NameData TypeDescription
image_urlstringUrl to the original scanned, hand-marked map
file_idstringHash of image_url, to identify files.
source_filestringSource file for the annotation data
url_yearintegerYear of the observation, from the URL to the image
url_monthintegerMonth of the observation, from the URL of the image
datedateDate of the observation, either from the annotation on the map, or from the URL.
neighborhoodstringNeighborhood name
url_neighborhoodstringNeighborhood name, from the URL
total_countnumberTotal count for all sleepers.
tempintegerTemperature, F
rainstringRain or clear

### raw_file_annotations

Column NameData TypeDescription
image_urlstringUrl to the original scanned, hand-marked map
datedateDate of the count, or the first of the month if the day of the date isn’t specified.
neighborhoodstringNeighborhood name
total_countnumberTotal count for all sleepers.
tempintegerTemperature, F
rainstringRain or clear
source_filestringSource file for the annotation data

### gcp_transforms

Column NameData TypeDescription
urlstringUrl to the original scanned, hand-marked map
neighborhoodstringNeighborhood name
sourcestringThe intersection polygon, formed from the intersection points, in WKT format, in the pixel coordinate space. This version is inverted from the coordinates of the image, with the Y coordinate being subtracted from 2000, so the orientation of the Y axis is the same as the EPSG:2230 geographic coordinate space.
deststringThe intersection polygon, but in EPSG:2230 (State plane 6, California, Feet) coordinates.
matrixstringAn affine transformation matrix that transforms from the coordinates of source_inv to dest. When pixel locations are properly inverted, this matrix transforms from pixel locations to geographic locations.

### raw_gcp

Column NameData TypeDescription
image_urlstringUrl to the original scanned, hand-marked map
xintegerX position of upper left of region rectangle, in pixels
yintegerY position of upper left of region rectangle, in pixels
widthintegerWidth of selection region rectangle in pixels
heightintegerHeight of selection region rectangle in pixels
intersectionstringName of intersection

### raw_count_annotations

Column NameData TypeDescription
image_urlstringUrl to the original scanned, hand-marked map
cxintegerX value of the center of the circle region, in pixels
cyintegerY value of the center of the circle region in pixels
rnumberRadius of the circle region, in pixels
typestringType of sleeper: Individual, Vehicle or Structure
countintegerCount of sleepers

### intersections

Column NameData TypeDescription
geometrystringPoint position of center of intersection, EPSG:2230, California State Plane 6
neighborhoodstringNeighborhood name
intersectionstringIntersection name