Overview
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P-codes are unique geographic (geo) identification codes, represented by combinations of letters and/or numbers to identify a specific location or feature on a map or within a database. For For a specific place, point, or positional locationslocation, the geo-codes have come into common usages as P-codes (abbreviated abbreviation for Place-Code). These terms can be essentially interchanged as long as one recognizes the focus on “position or place” for P-codes. There can only be only one pP-code per administrative unit. They are also used to provide unique reference codes to refer to settlements or administrative units in other datasets.
P-codes should be made available as a preparedness activity during the development of the Core CODs (COD-AB and COD-PS). At a minimum, the taxonomy (names and pP-codes) should be made available as a gazetteer.
P-codes will be required and used at the very start of an emergency and throughout the response. P-codes help with data coordination and provide the framework for most data collection, processing, analysis, and visualization. For instance, P-codes/names are used to create the 3W 3W and monitoring data collection frameworks. They are used to help process data such as when processing country-specific CODs (e.g. putting , assigning P-codes in to school locations). P-codes are used for analysis such as a prioritization matrix or a vulnerability matrix. P-codes are also used to visualize humanitarian data in maps and charts as seen in HDX, Snapshots, Bulletins, HNOHNOs, etc).
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P-coding process
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The first and most important two steps are: 1) confirm that there is no national coding scheme already available; 2) confirm that there is no informal coding scheme that has been adopted by some national or international organizations. Only proceed to create a P-code system if no other system is available.
The schematic below shows a basic structure of a P-code system for a country with four administrative boundary levels.
The components of this system are:
Country Code - This is taken from the ISO 2-letter country code standard. For most purposes, this code does not need to be included when giving the P-code for a place. However, a good reason for including it is that it This will force any P-code to be recognized as text rather than a number, which has the advantage of being sure that leading zeroes are not dropped reduces dropped and reduces the risk of database key incompatibility.
Admin Administrative level 1 to Admin Administrative level x - Each admin administrative level gets receives a numeric code with enough leading zeros to ensure that the occasional addition of new admin administrative units will not exceed the number of digits codes available. In the example below, two digits are adequate for admin administrative levels 1 - 3 (meaning that there will are not expected to be more than 99 admin administration units in any one of these levels). Level 4 can have as many as 999 admin administrative units.
Incremental Settlement Numbers (if required) - For simplicity of maintenance, it is best to use a single set of incremental numbers across the whole country (rather than within each admin administrative unit). This has the additional advantage of allowing places to be referred to using only the settlement number without the admin unit codes, making them shorter. Enough digits should be used here to allow for the possibility of new datasets to be added.
How How much structure is too much?
There is a temptation to "over-structuredstructure" the P-code system, for example, having a contiguous range of Admin level 2 codes falling within a given Admin Level 1 boundary. However, these sort of restriction, especially at the lower levels, are difficult to maintain over time and add little value to the P-code system.
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A given P-code can be removed (if a settlement or admin unit is removed), but never re-used to represent a different place place.
Additions to the settlements layer can be made at any time. However, partners should be notified when this is done.
Deletions in the settlements layer or any change to the admin administrative units must be coordinated across the humanitarian community so that all actors switch to new versions of the admin units at the same time.
Standards
- P-codes are must be unique within a country (no duplication of pP-codes).
- There can only be only one pP-code per administrative unit. (There
- Pcodes P-codes in the COD-AB and COD-PS should on a 1:1 should match.
- At a minimum, the taxonomy (names and pP-codes) should be made available as a gazetteer even if the administrative boundary geometry is unavailable.
- Ideally, a P-code is a combination of letters and/or numbers (see image above) but national systems should be adopted. If no alpha code (usually it is ISO 2 letter code) is used nationally, it may need to be added to ensure its uniqueness globally.
- P-codes must be included in the COD-AB and COD-PS. It is best practice to include pP-codes in other COD datasets (e.g., use spatial join/union with COD-AB)
Resources
- P-code Guidance Process to develop P-codes produced by OCHA, UNHCR, and the International Center for Remote Sensing Education.
- P-code flyer (for advocacy purposes).
P-Coder coder tools: these tools will analyze an excel spreadsheet and verify names/p-codes. Used when processing partner 3W or monitoring data. These can be modified to fit other country needs.
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Tutorial