将获得的变量输入python中的Overpass API调用

Question

Using code I obtained from the following link : http://python-overpy.readthedocs.org/en/latest/example.html I want to instead input variables that I have already obtained instead of directly inputting them,such as follows:

import overpy
api = overpy.Overpass()
result = api.query("node(min_lat,min_lon,max_lat,max_lon);out;")
len(result.nodes)

The variables min_lat etc are of type float. This is the error I am getting:

overpy.exception.OverpassBadRequest: Error: line 1: parse error: Unknown query clause 
Error: line 1: parse error: ')' expected - 'min_lat' found. 
Error: line 1: parse error: An empty query is not allowed 
Error: line 1: parse error: Unknown type ";" 
Error: line 1: parse error: An empty query is not allowed 

Any help is greatly appreciated as I am quite stuck and new to all of this thank you!

Answer 1

You are literally sending the query node(min_lat,min_lon,max_lat,max_lon);out; to the Overpass API, min_lat etc. are unchanged.

To fill the variables you can use string substitution:

"node(%s, %s, %s, %s);out;" % ( min_lat, min_lon, max_lat, max_lon )

The %s will get replaced with the variables you supply in the brackets.

import overpy
api = overpy.Overpass()

min_lat = 50.745
min_lon = 7.17
max_lat = 50.75
max_lon = 7.18

query = "node(%s, %s, %s, %s);out;" % ( min_lat, min_lon, max_lat, max_lon )
result = api.query(query)

print query
print len(result.nodes)