NumPy is a Python module, adding support for large, multi-dimensional arrays and matrices, along with a large library of high-level mathematical functions to operate on these arrays.

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15
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3answers
9k views

Writing numpy array to raster file

I'm new to GIS, and I'm lost with something I feel ought to be relatively simple. I have some code that converts infrared images of Mars into thermal inertia maps, which are then stored as 2D numpy ...
13
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1answer
1k views

How can I utilize NumPy arrays to optimize big data geoprocessing?

I'm interested in learning how to utilize NumPy arrays to optimize geoprocessing. Much of my work involves "big data", where geoprocessing often takes days to accomplish certain tasks. Needless to ...
11
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3answers
10k views

How to fully load a raster into a numpy array?

I have been trying to check my filters on DEM raster for pattern recognition and it is always resulting in missing last rows and columns(like..20). I have tried with PIL library, image load. Then with ...
11
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3answers
1k views

How to convert LAS file to numpy array?

I have begun learning how to manipulate LAS data in python and wanted to see how others handle LAS files. I would like to read the points (I am using a numpy array), and filter out classes 1 and 2 ...
10
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2answers
2k views

How to keep spatial reference using arcpy.RasterToNumPyArray?

I am using ArcGIS 10.1, and want to create a new raster based on two preexisting rasters. The RasterToNumPyArray has a good example which I want to adapt. import arcpy import numpy myArray = ...
10
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3answers
3k views

Gdal Dataset.ReadAsArray() crashes Python

I am using Python 2.6.5 (32bit) with Numpy 1.3 and Gdal 1.9.1 installed on Windows 7 64bit. I am trying to read an 800 MB Imagine (.img) raster dataset into a Numpy array to do some raster algebra, ...
9
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1answer
224 views

PySAL natural breaks from Numpy array

I am attempting to extract natural break values from a raster using Python. The intended process goes: Arcpy raster object to NumPy Array (using RasterToNumPyArray) to natural break values (using ...
7
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1answer
364 views

Why is matplotlib installed with ArcGIS?

Today I upgraded to ArcGIS Desktop 10.2.2 as well as the 64-bit background processing tool and noticed that both numpy and matplotlib were installed with Python. In fact, in the "What's New?" section ...
6
votes
2answers
819 views

Downloading raster data into python from postgis using psycopg2

I have raster data in a postgres table that I want to get into python as a numpy array. I am using psycopg2 to connect to the db. I am able to download the data but it comes back as a string (probably ...
6
votes
1answer
1k views

Subsetting GeoTIFF with Python

I'm sub-setting a GeoTIFF with the GDAL Python binding and numpy. Essentially, I am providing a central location (coordinates of a flux tower) from which I produce a subsetted image. I then want to ...
6
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1answer
1k views

Replicating result of gdalwarp using gdal Python bindings

I am trying to re-project/resample with the GDAL python bindings, but am getting slightly different results compared to those from the command line utility gdalwarp. See update below for shorter ...
6
votes
3answers
453 views

How to get QGIS to play with pandas (Windows)?

has anybody been successful getting pandas to work with QGIS's Python installation, on Windows? I've used the OSGeo4W installer to install QGIS2.2, which comes with Python 2.7 and Numpy 1.5.1. Any ...
6
votes
1answer
691 views

ArcGIS Desktop 10.1 SP1: how to install/use additional Python modules?

I'm currently working on a project where I have to identify geomorphological features in a digital elevation model. Since the aim is to have a single ArcGIS Toolbox integrating all processing steps in ...
6
votes
0answers
439 views

Save fails on raster object created from NumpyArrayToRaster [closed]

I am trying to save an ESRI grid built from a numpy array and am getting an error I've never seen before: Unhandled Exception: System.IO.FileNotFoundException: Could not load file or assembly ...
5
votes
2answers
4k views

Obtain coordinates and corresponding pixel values from GeoTiff using python gdal and save them as numpy array

How to obtain projected coordinates as well as the actual pixel values at those coordinates from GeoTiff file and then save them into a numpy array? I have arsenci020l.tif file, and its coordinates ...
5
votes
2answers
603 views

Creating numpy.array with variable number of fields to test arcpy.da.ExtendTable performance?

There was an ArcPy Café blog posting entitled Adding Fields: Performance Tips which advocated: Two approaches to help increase performance when adding numerous fields to a table or feature ...
5
votes
2answers
638 views

Adding noise to a raster

I want to add some fine-grained noise to a raster in an automated python process (i.e. I do not want to use Photoshop or GIMP). I looked at PIL, but unless I'm mistaken, it doesn't seem to have any ...
5
votes
1answer
766 views

raster algebra in python with rasters of different extents

I am trying to find out how to use GDAL & numpy modules to average a set of rasters....which are Sigma0 values from satellite passes at different times within a year. Each raster has been ...
5
votes
2answers
348 views

What's the most efficient way to load feature attributes into a numpy array?

I am currently working on an add-on that relies on the user choosing fields of tables (that can be from shapefiles, csv or dbf) that are open in QGIS and then making computations with such data. ...
5
votes
2answers
1k views

Installing both ArcGIS for Desktop and Python(x,y) on same machine?

I'm trying to get ArcGIS 10.1 and Python(x,y) to peacefully co-exist with a unified installation of Python. Surely someone else is using both these tools... right? Here's where I've gotten to: ...
5
votes
1answer
135 views

Optimizing Python GDAL ReadAsArray

I am using the GDAL ReadAsArray method to work with raster data using numpy (specifically reclassification). As my rasters are large, I process the arrays in blocks, iterating though each block and ...
4
votes
4answers
450 views

Raster reclassify using python, gdal and numpy

I would like to reclassify a raster file from a raster with 10 classes to a raster with 8 classes using pyhton, gdal and/or numpy. The classes are represented as integers. I have tried following the ...
4
votes
1answer
887 views

How to change value of an individual pixel using arcpy?

I want to change the value of an individual pixel in a raster using arcpy. The code I wrote for changing the value is below, but it changes all of pixels in my raster. How can I set an individual ...
4
votes
2answers
280 views

Reconstructing MODIS time-series applying Savitzky-Golay Filter with Python/Numpy

I want to apply the 'Savitzky-Golay' (savgol) filter to my time series, MODIS dataset, to remove noise (i.e., cloud pixels, etc.) in my data. MODIS have quality flags that indicates the reliability of ...
4
votes
1answer
54 views

Getting pixel values at single point using rasterio

To get a single pixel value at a point in a raster using rasterio, there is an example here: https://github.com/mapbox/rasterio/pull/275 However, is there a direct API within rasterio (and not the ...
4
votes
1answer
922 views

XYZ Clustering in Python and numpy arrays

I am looking for a method of clustering XYZ data in Python that works on numpy arrays. I know of a few sources, such as clusterpy and Pysal but have had little success with them as they seem to still ...
4
votes
2answers
291 views

How to publish GP Service with importing of numpy in ArcGIS for Server 10.1?

I use a lot of scripts as GP Service almost all use the arcpy functions but one (and very important) of my scripts needs a gdal/ogr and numpy imports. I can run this script in PyScripter or as a tool ...
4
votes
1answer
203 views

Tabulate Area using GDAL and Numpy

How could I perform a Tabulate Area using GDAL and Numpy? I am trying to summarize how many pixels of each class in a Landcover raster are within each polygon of a Census Blocks shapefile. I've ...
3
votes
2answers
176 views

Total count of values at each pixel in a raster stack/ 3d array

If you have an array with x, y and z dimensions, how can I create an array of x, y dimensions that holds a count of how many z values at each location (x,y) are noData? I would prefer to use numpy ...
3
votes
2answers
340 views

Efficient ways to read table data from a large feature layer?

I have a feature layer that contains about 460,000 records and it currently takes about 20 minutes to read that table using the arcpy.da.TableToNumPyArray() tool. Is there a more efficient way to read ...
3
votes
1answer
280 views

Reclassify a raster value to -9999 and set it to the nodata value using python and or gdal

I modified a script which reclassifies a raster. It is based on the script by Roger in his blog (the second script) and it works pretty well.The problem I am facing is as follows: I would like to ...
3
votes
1answer
196 views

Downsampling Geotiff using summation - Gdal/Numpy

I am trying to downsample a 1 square km raster dataset to a much larger (.5 degree x .66 degree) dataset by summing all of the pixel values within this large grid cell. gdal_warp does not contain a ...
3
votes
2answers
409 views

Memory and Processing Efficient Approach to Read a Timeseries in Python

I am trying to store a timeseries of high resolution raster images containing NDVI values into a dictionary for calculations. I am curious as to which approach may the most efficient when loading ...
3
votes
1answer
2k views

Iterating through an numpy array and index to a value in another numpy array

I am struggling to get this code to work I want to iterate through an numpy array and based on the result, index to a value in another numpy array and then save that in a new position based on that ...
3
votes
1answer
70 views

Memory error in python when reclassifying array

I have a .tif that I read into an array (call it tifArray), and I would like to classify the array based on set of conditions: Where 1200 <= tifArray <= 4000, outputArray = 1 Where tifArray ...
3
votes
2answers
208 views

Finding the pixel coordinates using GDAL/numpy

Is there a way to get the XY cordinates of a pixel based on the array index using numpy/gdal? I have a new set of extents for a raster and, based on these newer extents, want to determine the ...
3
votes
1answer
184 views

QGIS Contour Plugin Says No Shapely; can import shapely in QGIS console

I'm keen to create some contours (isochrones for a pedestrian 'ped-shed' catchment) from a point dataset in QGIS, using the contour plugin from the Plugins repository. I installed the plugin, but ...
3
votes
1answer
704 views

Selecting raster values at random locations in a raster in python/arcgis

I have a large dataset of integer rasters, and was hoping to find a way to generate a "random" selection of pixels for four of the rasters, while making sure all 5 classes, which I've specified based ...
3
votes
2answers
769 views

PostGIS + pgRouting: Adding dummy links to a road network and performing routing analysis

I'm a beginner when it comes to postgis and pgrouting development. For a project I'm working on and a bit of the algorithm: I have a polygon layer that represents zones I have a line layer that ...
3
votes
1answer
365 views

Converting large rasters to NumPy

I have a geodatabase that contains a large number of raster datasets - there are two rasters for each country in the world, and they are very large, in some cases up to 3GB per raster dataset. I ...
3
votes
0answers
47 views

GDAL RasterIO performance in C++ vs ReadAsArray in python/numpy

I'm currently writing optimisations for a raster viewer program which uses gdal as it's base. It's currently written purely in python, and has some major speed issues which cause problems when we are ...
3
votes
0answers
83 views

Select shape file by their coordinates behavior [closed]

I want to filter shapefiles by their latitude behaviour: If the latitudes of edges A and B are constantly decreasing or increasing then this class marked as correct, otherwise are incorrect. For ...
3
votes
0answers
531 views

How does gdal_calc numpy operators work?

Gdal_calc manual Gdal_calc is introduced as : gdal_calc.py - Command line raster calculator with numpy syntax gdal_calc.py [-A <filename>] [--A_band] [-B...-Z filename] [other_options] ...
3
votes
0answers
500 views

Buffering a Raster with GDAL and Numpy

I am using GDAL to convert a raster dataset into a numpy.array and then using numpy to buffer the data in the raster. For example, I need to know all the regions within 100ft of a school point ...
2
votes
3answers
3k views

Is it possible to open rasters as array in NumPy without using another library?

I know that it is possible to open a raster as an array in NumPy using GDAL, but I want to skip GDAL and use NumPy only, as it is cooler handling rasters with NumPy as matrices. There is a similar ...
2
votes
1answer
1k views

Installing pandas with Esri's python?

Trying to get pandas to import, but I'm getting what looks like an error caused by a failed dependency of the version of my Esri-provided numpy's compile, based on this stackoverflow posting. Here's ...
2
votes
1answer
3k views

Display a georeferenced DEM surface in 3D matplotlib

I want to use a DEM file to generate a simulated terrain surface using matplotlib. But I do not know how to georeference the raster coordinates to a given CRS. Nor do I know how to express the ...
2
votes
1answer
553 views

Calculating beta-diversity w raster data [renamed]

Using ArcGIS 10, it is not possible to generate a raster attribute table for 32-bit float values. Instead, I have tried the RasterToNumPyArray method, which crashes since the file input raster is so ...
2
votes
2answers
98 views

Numpy error when computing scores based on percentiles

I want to calculate scores in one field based on the percentile (in steps of 10) the row falls into in another field. I found a solution here (Calculating Percentiles in ArcMap?) that I tried out, ...
2
votes
1answer
440 views

Migrating data from Python to PostGIS

I have pandas DataFrame with these columns: point datetime value 1 Point(-24.6064453125 26.3683280945) 2014-09-11 19:00:00 24.885258 2 ...