Read and write vector files with GDAL/OGR in Python

This tutorial explains how to open vector files with GDAL/OGR in Python, add attribute fields to store measures such as the perimeter and area of a polygon, and save the updated features to a new shapefile. We will also look at how to create a geometry from individual coordinates in Python and write it to a new vector file.

Code:
from osgeo import ogr

# open shapefile
layer = ds.GetLayer()

# get extent
ext = layer.GetExtent()

# get a single feature
feature = layer.GetFeature(1)

# loop over all features in a layer
for feature in layer:
print(feature.GetField("FID"))

# create new shapefile
driver = ogr.GetDriverByName("ESRI Shapefile")

# copy layer
outlayer = ds.CopyLayer(layer, "out")

# create a new attribute field
newfield = ogr.FieldDefn("Perimeter", ogr.OFTReal)
newfield.SetWidth(10)
newfield.SetPrecision(3)
outlayer.CreateField(newfield)

# get the perimeter of each polygon
for feature in outlayer:
geom = feature.GetGeometryRef()
perim = geom.Boundary().Length()
feature.SetField("Perimeter", perim)
outlayer.SetFeature(feature)

# close everything
outlayer = outds = feature = None

# create a ring geometry from the extent of the merged layer
ring.AddPoint(ext[0], ext[2])
ring.AddPoint(ext[1], ext[2])
ring.AddPoint(ext[1], ext[3])
ring.AddPoint(ext[0], ext[3])
ring.AddPoint(ext[0], ext[2])

# convert to polygon
poly.AddGeometry(ring)

# save to shapefile
outlayer = outds.CreateLayer("extent", layer.GetSpatialRef())
feature = ogr.Feature(outlayer.GetLayerDefn())

feature.SetGeometry(poly)
outlayer.CreateFeature(feature)

outds = outlayer = feature = None

[michaelmeadows]

Great playlist, thank you for these, excellent resource for learning GDAL! A note for anyone else having trouble with the final feature not being updated (i.e. perimeter value of final feature still null when opened in QGIS): make sure you close the feature (as noted at minute 10:12) *within* the for loop (as the final line).

[shishirnair]

I was struggling with ogr vector functions. Thank you Making Sense Remotely, you made learning such a breeze. I look forward for more content and learnings from your channel. Know that your work and efforts are highly appreciated by those who work in GIS field.

[agerman]

Wow, thanks so much. Clear voice/sound and explanations. Waiting for more :)

[MusicallyDisturbed]

reallly helpful and gave very nice overall understanding of OGR vector operations!! thank you

[colorizedenhanced-silentmo]

salutations, Making Sense Remotely. pretty good video. thanks. :)

[JeewantinieKapilaratne]

Thank you very much for your grate lesson. I have encountered following issue "KeyError: 'Illegal field requested in GetField()'" when I tried to access "FID" field .However, I was able to access other fields of the layer. Would like to hear any clarification/comment on this

[Ryan-tfix]

If you could link the files (.shp and .tif) you are using in your tutorials it would make them a lot easier to follow. Thanks!

[sebastianmartijena]

Thank you very much! Also for the code

[erinlindsay]

I am looking for a video on how to convert a list of coordinate points from, for example UTM, to lat long, using gdaltransform. Have you already covered this? If not, I would find it very helpful. That is my main reason for wanting to use gdal.

[nikhilkumarkulkarni]

How to rotet tif file actioly im trying open tiff file using python but i can able to load but if compated to global mapper image is looking like mirrer image kindly help me to solove this issue

[umairrasool]

I am working with raster data for ANN, i have converted rasters to numaric and then test train that numerical data and get very Good accuracy. now i need to convert my train data into raster but i don't know how. please guide me.

[aichamoumni]

That's very wonderful and helpful, thank you! please I am beginner in python and I just tried to run my first script but I got an error as following:
"from osgeo import gdal

ImportError: No module named osgeo"
I already installed gdal but it's not working, please could you help me with this?