Mapping Local POIs Part 1: How many hairdressers does one barrio need?
Posted by alan_gr on 28 October 2024 in English. Last updated on 29 October 2024.Recently I have been trying to systematically improve OSM data about shops, businesses, and other Points of Interest in a small area of my city. Like many OSM contributors before me, I have been torn between the desire to make my local map as complete as possible, and the realisation of just how much time is needed to do that. My observations in the following series of diary posts may not be very original, but perhaps they’ll help me to clarify my thoughts on the subject.
Background
Málaga is divided into about 200 barrios or neighborhoods, all with well-defined boundaries in OSM. I chose to focus on an area of four adjoining barrios slightly to the northeast of the historic centre. The main axis of this area, formed by Calle Victoria and Calle Cristo de la Epidemia, is about 1km long (the green dashes in the map below). These main thoroughfares, and many of the smaller streets, are lined by apartment blocks with commercial premises on the ground floor. The hillier areas to the east are more purely residential. Most shops are quite small, many are sole traders, and there are no shopping malls.
To be clear, I am not claiming this area is representative of anything but itself. Even in the same city, there are neighbourhoods with denser concentrations of POIs due to shopping malls, and areas that are almost entirely residential with very few POIs.
Various OSM contributors have added POI data here over the years, with a particularly big effort in 2017. I have updated individual POIs from time to time when I noticed changes, but I was aware that I hadn’t been very diligent about this, so there was probably quite a lot of outdated data. Still, I reckoned POIs in the area were reasonably well mapped, and that it wouldn’t take too long to add some missing shops and update others.
Spoiler: I was wrong.
Complete data … almost
Over the period of the survey (about 2 months), the number of POIs increased from 258 to 376.
I will talk about the reasons behind that change in a future diary entry. But first, I want to look at the data as it is now. Often discussions of OSM POI data have to start from the assumption that the data is incomplete. Looking at “my” area just after a survey gives us a chance to consider an “almost complete” OSM dataset.
Why only “almost”? There are a few reasons: * The definition of a POI is inevitably arbitrary. My definition is essentially “everthing tagged in OSM as shop, amenity, office, healthcare, craft, and tourism, EXCEPT things I decided to exclude”. Those exceptions are mainly high-volume tags such as individual parking spaces, waste/recycling facilities, and street furniture such as benches. * Some offices are identifiable only by a small plaque in a doorway, and I didn’t go out of my way to find all these (although I did try to confirm those already mapped). * Local business owners thoughtlessly went on doing things like retiring and selling their businesses while I was in the middle of my surveying effort, so I was never quite sure of being up to date. * I probably just got some things plain wrong.
Current POIs: Some numbers
POIs by type
The 376 POIs (according to my definition above) fall into these broad groups:
feature_group | frequency | frequency_pc |
---|---|---|
amenity - food+drinks | 56 | 14.9 |
amenity - general | 48 | 12.8 |
craft - general | 14 | 3.7 |
healthcare - general | 26 | 6.9 |
office - general | 42 | 11.2 |
shop - clothes | 15 | 4.0 |
shop - food | 52 | 13.8 |
shop - for the body | 51 | 13.6 |
shop - general | 61 | 16.2 |
tourism - general | 11 | 2.9 |
I have defined a few large groupings following Vespucci/JOSM presets, with everything else falling into “general”. Both “amenity - general” and “shop - general” cover a very diverse range of other POIs.
A plot of these points shows that POI types are fairly well mixed throughout the area. The mainly residential northeast corner is an exception - the POIs here are mainly tourist accommodation.
Tag distribution
The 376 POIs are mapped by 116 distinct feature tags (amenity=bank, shop=supermarket and so on). The most common single tag is “hairdresser” with 29 uses, some way ahead of “cafe”, “restaurant”, and “fast_food”. At the other end of the scale, 52 tags are used only once. Only 21 of the 116 tags are used more than 4 times.
Within the “office” grouping, “estate_agent” and “property_management” accounted for 17 POIs between them - possibly a reflection of the growing importance of vacation rentals.
Main streets v side streets
One thing that surprised me was the number of premises on side streets. I previously had the impression that most POIs were along the main axis I mentioned above, plus Calle Ferrándiz which branches off to the east.
Spoiler: I was wrong again.
In fact 55 percent of POIs were on other streets.
Even extending the definition of “main street” a bit further (roughly to anything classed as tertiary or above in OSM), a healthy 45 percent of POIs were on side streets.
How many hairdressers?
While surveying the zone I gradually started to become haunted by a feeling that I was spending most of my time mapping hairdressers, barbers, and beauty salons. (Many such places label themselves “Peluquería - Estética”, so any distinction between hairdressers and beauty salons is rather arbitrary). It felt quite appropriate that I ended up mapping the Association of Ladies’ Hairdressers (as an association, not a hairdresser).
It turns out that 38 POIs, about 10% of the total, are hair/beauty shops. Comparing with shops rather than all POIs, that’s more than 21% of shops - compared to 10% in OSM worldwide. At face value that supports my impression that this particular area is strangely oversupplied with hairdressers.
But there is another possibility: maybe it’s quite normal for one in five shops to be hair and beauty salons, and it’s the 10% global OSM figure that is misleading. Perhaps these businesses are typically small and run by sole traders, and get less attention from mappers than larger shops or brands. That was certainly the case in my area until my recent systematic mapping.
In my next diary entry I’ll look at brands … and their absence.
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