Lines in Polygon Analysis

Question

This question is similar to the "points in polygon" analysis, but I want to keep the attribute data for multiple lines within a single polygon. The data source is multiple line segments representing weather data, and I want to add the attributes of each line inside a geographic region (country shapefile). For example, the resulting polygon might have 10 rows for "India" and each row represents a unique set of weather data. Each row is the actual data from a line shapefile that falls within the "India" geography.

I've tried spatial join (and several other options), but this summarizes the datasets by polygon and does not preserve original attributes (unless I am missing something).

Answer 1

While point in polygon means one-to-many connection, e.g. a point is inside 0 or 1 polygon. The polyline in polygon problem is more complex, a polyline may intersect several polygons. So to do the job you should use overlay operation, not spatial join.

The overlay intersection operation creates a new layer in which the polylines are broken at the polygon borders and polygon attributes are added to the result layer. For example, the input data:

Vector/Geoprocessing Tools/Intersection:

The result of intersection:

Update Other solution to preserve polygon geometry: You can use use spatial join to create a new layer from Vector/Data Management Tools/Join Attributes by Location menu.

In the result layer you get repeated polygons.