How to convert length in Decimal degrees to meters programmatically?

Question

I'm new to qgis and I want to find the length of some roads in a map. So I used the following code,

from shapely.wkb import loads

def getLength():

layer = qgis.utils.iface.mapCanvas().currentLayer()
total = 0
for feature in layer.selectedFeatures():
    geom = feature.geometry()
    wkb = geom.asWkb()
    line = loads(wkb)
    total = total + line.length
return total

print getLength()

It shows the length in degrees I think. Is there any way to convert the result I got to meters, without changing the CRS of project. I want to do it programatically(without adding new field using field calculator).

Answer 1

One option would be to use the processing qgis:reprojectlayer to reproject the selected features and save them to an in memory layer. Once you have this layer then use the QgsGeometry length() method noted by Nathan W to get the feature length in meters.

# make sure you have selected features first
import processing
result = processing.runalg('qgis:reprojectlayer', layer, "EPSG:102013", None) # change EPSG value to desired CRS
inMemoryLayer = processing.getObject(result['OUTPUT'])
# continue on and get feature geometry length...