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Volunteered Geographic Information » ArcGIS 10 – Field Calculator and Python

Volunteered Geographic Information » ArcGIS 10 – Field Calculator and Python | Geoprocessing | Scoop.it

Python has been more tightly integrated in the new release of ArcGIS 10, allowing scripting to occur directly through a Python process without even opening up ArcMap. Admittedly this was available before, but now everything is more tightly coupled and a lot cleaner in it’s implementation. However, what has really interested, and indeed confused me of late is how to use Python in the ‘field calculator’.

 

Field Calculator is a really useful tool, when you are looking at an attribute table for a shapefile in ArcGIS and you want to derive a value for each object in the file based on a function you can input the function into the field calculator and it will work it out for you row by row. Sometimes the value you want to derive is a bit more complicated than simple arithmetic and you need to write a script. Previously you could do this in VBA, but I always found it limited and confusing, now however you can do it in Python – much simpler!

 

There are a few pitfalls to using Python in ArcGIS field calculator, and so I’m going to specify how to write simple field calculator python scripts in ArcGIS from my early experience.

 

Firstly, for Python in field calculator the way to do it seems to be in write a Python function, and then call it for each row. In addition to this, because you are writing a function you have to give it the relevant parameters (i.e fields) with which to do the computation. Finally, and annoyingly you have to write your function in a little box, and use a consistent indentation standard (1 space works best for reasons of space) as Python requires.

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Alexandre Neto's blog: Etiquetas com guias em QGIS e Postgis | Labels leading lines with QGIS and Postgis

Alexandre Neto's blog: Etiquetas com guias em QGIS e Postgis | Labels leading lines with QGIS and Postgis | Geoprocessing | Scoop.it
“Recentemente tive necessidade de colocar etiquetas de texto em elementos com geometrias muito próximas, fazendo com que as mesmas colidissem umas com as outras.”
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GeoPlanner for ArcGIS

GeoPlanner for ArcGIS | Geoprocessing | Scoop.it
“Ken Gorton explica aqui como o GeoPlanner se está a tornar numa ferramenta para geodesign cada vez mais poderosa.”
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MDE em zonas costeiras: Alguns Desafios

MDE em zonas costeiras: Alguns Desafios | Geoprocessing | Scoop.it
“A criação de MDE (Modelos Digitais de Elevação) e os desafios de sua utilização em Zonas Costeiras foi tema de um artigo publicado no Journal of Coastal Research , nesse mês de Setembro.”
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ArcGIS Solutions for Water Conservation

ArcGIS Solutions for Water Conservation | Geoprocessing | Scoop.it
Water is arguably our most precious resource, and one we simply cannot live without.  Utilities today are facing unprecedented water shortages due to multiple factors: drought, increasing population needs, and increasing agricultural demands.
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Aprenda a baixar imagens Landsat-7 no site Earth Explorer

Aprenda a baixar imagens Landsat-7 no site Earth Explorer | Geoprocessing | Scoop.it
 
Sobre o Earth Explorer
É um dos sites administrados pelo USGS onde é possível ter acesso ao material de domínio público. Todos os produtos da família Landsat podem ser baixados através desse site, que possui uma interface gráfica muito amigável.
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Python in QGIS and ArcGIS: A Small Example

Python in QGIS and ArcGIS: A Small Example | Geoprocessing | Scoop.it
Often the usage of GIS never touches the world of programming and I think a lot of GIS users today feel fine with using simple tools and try to avoid tools like Python for their daily work.
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Sistemas de Información Geográfica: 30 videos educativos

Sistemas de Información Geográfica: 30 videos educativos | Geoprocessing | Scoop.it
La geolocalización intrínseca en casi todo lo que hacemos, utilizando dispositivos electrónicos, ha logrado que el tema SIG sea cada día más urgente de aplicar.
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SRTM-1 (1 Arc second) now available with large global coverage

SRTM-1 (1 Arc second) now available with large global coverage | Geoprocessing | Scoop.it
“With this post I would like to come back on a topic from September 2014. In this blog post on Digital-Geography I announced that from September 2014 until September 2015 high-resultion SRTM-data will be provided for free by the USGS.”
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USGS: Aprenda a Baixar o DEM SRTM de 30m no site Earth Explorer

USGS: Aprenda a Baixar o DEM SRTM de 30m no site Earth Explorer | Geoprocessing | Scoop.it
“ Sobre o Earth Explorer É um dos sites administrados pelo USGS onde é possível ter acesso à dados de domínio público. Todos os produtos da família Landsat podem ser baixados através desse site, que possui uma interface gráfica muito amigável.”
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Short Announcement: “Quality Check” on SRTM1 | Geoprocessing | Scoop.it
“Well, I was expecting this. Damn, those new SRTM1 raster files provided via EarthExplorer by the USGS are sweet.”
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UAVs: The new trend in acquiring geospatial data through remote sensing | Geoprocessing | Scoop.it
“Learn why the world is looking forward for UAVs for collection and creation of aerial imagery”
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Semi-Automatic Classification Plugin v.4.0 Beta Available

Semi-Automatic Classification Plugin v.4.0 Beta Available | Geoprocessing | Scoop.it
“The beta version of the Semi-Automatic Classification Plugin v.4.0 "Frascati" is available through the the Facebook group and the Google+ Community. The main new features of the plugin are described in my previous post here.”
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Big, Bad Data

Big, Bad Data | Geoprocessing | Scoop.it
“Context is crucial in making big data useful, and the key to that context is often location. Move over, smart grid. A new buzz phrase has bumped you out of first place in utility IT: big data.”
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Dicas para possíveis erros ao fazer um CAR – Parte 2

“Muitas vezes são pequenos detalhes que atrasam a realização de um trabalho não é mesmo? Você começou a fazer um CAR, deu errado? Calma! Não precisa se desesperar!”
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Aprenda a baixar o Geocover no site Earth Explorer

Aprenda a baixar o Geocover no site Earth Explorer | Geoprocessing | Scoop.it
 
Sobre o Geocover
Geocover é um projeto de mapeamento da superfície terrestre a partir de mosaicos de imagens Landsat-7 do ano 2000.
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Risk of Flooding from Rivers and Sea Dataset Released as Open Data

Risk of Flooding from Rivers and Sea Dataset Released as Open Data | Geoprocessing | Scoop.it
The UK’s Environment Agency announced at the end of 2014 that it was releasing the Risk of Flooding from Rivers and Sea dataset (formerly known as the National Flood Risk Assessment dataset, NAFRA) as an open data resource.
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Análisis espacial con PyQGIS. Ejemplo: Merge

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Spatial Analysis and Introduction to Remote Sensing by Nancy Thomas - YouTube

Spatial Analysis and Introduction to Remote Sensing by Nancy Thomas

Via Yves Mulkers
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20 Trucos de QGIS que quizá no conocías

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“Operations Dashboard for ArcGIS just released it’s 10.3 update and you can download it from ArcGIS Online right now!”
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“This NEON Science video overviews what lidar or light detection and ranging is, how it works and what types of information it can provide. Continue reading → Click Title to Continue Reading...”
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Orfeo Monteverdi 1.22: Fusão de Imagens Landsat-7

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ArcGIS 10.2: Spatial Join – Contagem de Pontos no Poligono

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“ Sobre União Espacial Permite unir atributos de uma feição para outra baseado no relacionamento espacial. Utilize as técnicas de União Espacial do ArcGIS para obter o valor da contagem de pontos que estão contidos no polígono.”
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