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I have a GeoPackage that includes series of lines, each line corresponds to the itinerary of a person from point A to point B. I would like to know how to calculate the overlapping of lines (the superimposition has been made by the sna) and how to get to know which one are the most used itineraries.

I've already tried to use QChainage to get a heat map but I wondered if there was another way.

  • 1
    What's a "sna"? The School Nutrition Association? The ticker symbol of Snap-on Incorporated? – csk Nov 13 '18 at 19:31
  • Depending on the setup of your data, this may help: gis.stackexchange.com/questions/295022/… – csk Nov 13 '18 at 19:41
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If you are familiar with PyQGIS you could do something like this (QGIS 3.4.1):

# 'lines' is a polyline vector layer with one empty attribute field. 
# It could have more fields but remember to adjust the field index 
# in the attributes dictionary - {feature_number:{field_index:attribute_value}}

l = QgsProject.instance().mapLayersByName('lines')[0]

feats = l.getFeatures()

count = []

for f in feats:
    l.selectByIds([f.id()])
    j = processing.run('native:saveselectedfeatures',{'INPUT':l,'OUTPUT':'memory:target_line'})
    processing.run('native:selectbylocation', {'INPUT':l,'PREDICATE':7,'INTERSECT':j['OUTPUT'],'METHOD':0})
    s = processing.run('native:saveselectedfeatures',{'INPUT':l,'OUTPUT':'memory:selection'})
    t = len(list(s['OUTPUT'].getFeatures()))
    r = {f.id():{0:t}}
    count.append(r)

l_prov = l.dataProvider()

for i in count:
    l_prov.changeAttributeValues(i)

intersect count

Bear in mind that it counts intersecting features, not number of intersections.

  • I'm glad I could help. Does it solve what you were asking? – Matt Needle Nov 17 '18 at 6:14

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