spatialanalytics | 0 Workshop Code : Spatial Analysis
kandi X-RAY | spatialanalytics Summary
kandi X-RAY | spatialanalytics Summary
Where 2.0 Workshop Code: Spatial Analysis of Tweets using Hadoop, Pig, Python & Mechanical Turk. Slides here: http://www.slideshare.net/kevinweil/spatial-analytics-where-20-2010
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Top functions reviewed by kandi - BETA
- Read tweets from stdin .
- Generate a heatmap .
- Emits a list of ngrams .
- Load intensities from a CSV file .
- Clean a string .
- Return datetime from a given timestamp .
- Get the hour from the given timestamp .
- Find n - grams in sequence .
- Tokenize a text string .
- Initialize the message .
spatialanalytics Key Features
spatialanalytics Examples and Code Snippets
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Trending Discussions on spatialanalytics
QUESTION
I have two spatial datasets. One dataset contains lots polygons (more than 150k in total) specifying different features, like rivers, vegetation. The other dataset contains much less polygons (500) specifying different areas. I need to intersect those two datasets to get the features in the different areas. I can subset the first dataset by the different features. If I use a subset from a small feature (2,500 polygons) the intersection with the areas is quite fast (5min). But if I want to interest a bigger feature subset (20,000 polygons) the computation runs really long (I terminated it after two hours). And this is not even the biggest feature (50,000 polygons) I need to intersect.
This is the code snipped I run:
...ANSWER
Answered 2019-Nov-19 at 10:33As there probably won´t come a real answer to this vague question I will answer it on my own.
Thanks @Chris and @TimSalabim for the help. I ended up with a combination of both ideas.
I ended up using PostGIS which is from my experience a pretty intuitive way to work with spatial data. The three things which speeded up the calculations of intersection for me are:
- In my chase the spatial data was stored in MULTIPOLYGONS when loading from shapefile. I expanded those into POLYGONS using ST_DUMP: https://postgis.net/docs/ST_Dump.html
- I created a Spatial Index on the POLYGONS: https://postgis.net/workshops/postgis-intro/indexing.html
- I used a combination of ST_Intersection and ST_Intersects to only call the costly ST_Intersection when realy needed (As @TimSalabim suggested, this approach could also speed up things in R....But I currently have no time to test this approach): https://postgis.net/2014/03/14/tip_intersection_faster/
QUESTION
I have some large shapefiles with multiple millions of polygons that I need to dissolve. Depending upon the shapefile I need to either dissolve by group or just use st_union
for all. I have been using the st_par
function and it has been working great for most sf applications. Though when I use this function on st_union
it returns a list and I cannot figure out how to parallize the sf dissolve function st_union
.
Any suggestions would be most helpful! Here is a small code snippet to illustrate my point.
...ANSWER
Answered 2018-Feb-15 at 10:04I think you can solve your specific problem with a small modification of the original st_par
function.
However this is just a quick and bold fix and this might broke the code for other uses of the function.
The author of the function could certainly provide a better fix...
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Install spatialanalytics
You can use spatialanalytics like any standard Python library. You will need to make sure that you have a development environment consisting of a Python distribution including header files, a compiler, pip, and git installed. Make sure that your pip, setuptools, and wheel are up to date. When using pip it is generally recommended to install packages in a virtual environment to avoid changes to the system.
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