Get total vertex count for a shapefile

by Derek Swingley

I needed a quick way to get the total vertex count in a shapefile. The ogrinfo command includes vertex count in its output. This command: 

$ ogrinfo -dialect SQLite -sql "SELECT sum(ST_NPoints(geometry)) AS vertex_count FROM OK_second_congressional_district" OK_second_congressional_district.shp

yields: 

INFO: Open of `OK_second_congressional_district.shp'  
      using driver `ESRI Shapefile' successful.

Layer name: SELECT  
Geometry: None  
Feature Count: 1  
Layer SRS WKT:  
(unknown)
vertex_count: Integer (0.0)  
OGRFeature(SELECT):0  
  vertex_count (Integer) = 203

But that is a lot to type (and remember).

Since the only thing that changes between running commands is the name of a shapefile, it's easy to call this from a shell script:

#!/usr/bin/env bash
printf "\nLayer: $1\n"  
ogrinfo -dialect SQLite -sql "SELECT sum(ST_NPoints(geometry)) AS vertex_count FROM $1" $1.shp | grep "vertex_count (Integer) ="  
printf "\n"

Using $1 says take the second argument (in our case, the name of a layer / shapefile) and use that in the ogrinfo command.

To use this script, save it as file as somewhere (I called it vc), make it executable, copy it to a directory in $PATH, and now it's much easier to get that count I wanted:

$ vc OK_second_congressional_district

Layer: OK_second_congressional_district  
  vertex_count (Integer) = 203