Difference between revisions of "Geo Spatial Data"

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Although dealing with limited amount of data, and maybe having acquired the data from formal sources, GIS data need a stringent review, which often lead to quite an amount of cleaning. Most of the time you will spend in using GIS data will/should be spent there.
 
Although dealing with limited amount of data, and maybe having acquired the data from formal sources, GIS data need a stringent review, which often lead to quite an amount of cleaning. Most of the time you will spend in using GIS data will/should be spent there.
  
===Subsection 3===
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===Use of intersection to produce usable data for Stata===
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-For a particular project that has a spatial component, you first need to have geographical polygons that are representative of your project. For instance, the polygons that shows the limits of your villages.
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-Then, for some particular themes you will only find data in the form of GIS data. Examples of this are hospitals and clinics, or rainfall. The data in question is then intrinsically accompanied with coordinates, that allows to position the information in a spatial setting.
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-So then, after importing the particular data to a GIS software, you overlay your new data to the geographical layer that represents your project.
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-Once done, and simply intersect both layers, and ask for instance for a mean over your geographical polygons, or for a maximum or for a count. In QGIS, for instance, you will find a bunch of these useful spacial operations in the Vector/Geoprocessing Tools section.
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-These tools also allow you for instance to substract polygons from others; Then why not intersecting with data layer afterwards? It is much useful.
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-All that needs to be done then is to export your newly generated data.
  
 
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Revision as of 20:13, 7 February 2017

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Data Sources

You will find an immense amount of data sources online. Countries Statistic Offices often provide some, the USGS, the UN, Unicef, ect ect. What you will need for it to be the most useful, are either maps with vectorial layers that are (intrinsically) linked to datasets, or the datasets themselves.

Data Cleaning

Although dealing with limited amount of data, and maybe having acquired the data from formal sources, GIS data need a stringent review, which often lead to quite an amount of cleaning. Most of the time you will spend in using GIS data will/should be spent there.

Use of intersection to produce usable data for Stata

-For a particular project that has a spatial component, you first need to have geographical polygons that are representative of your project. For instance, the polygons that shows the limits of your villages. -Then, for some particular themes you will only find data in the form of GIS data. Examples of this are hospitals and clinics, or rainfall. The data in question is then intrinsically accompanied with coordinates, that allows to position the information in a spatial setting. -So then, after importing the particular data to a GIS software, you overlay your new data to the geographical layer that represents your project. -Once done, and simply intersect both layers, and ask for instance for a mean over your geographical polygons, or for a maximum or for a count. In QGIS, for instance, you will find a bunch of these useful spacial operations in the Vector/Geoprocessing Tools section. -These tools also allow you for instance to substract polygons from others; Then why not intersecting with data layer afterwards? It is much useful. -All that needs to be done then is to export your newly generated data.

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