я большой DataFrame с адресной колонкой:

      data   addr
0  0.617964  IN,Krishnagiri,635115
1  0.635428  IN,Chennai,600005
2  0.630125  IN,Karnal,132001
3  0.981282  IN,Jaipur,302021
4  0.715813  IN,Chennai,600005
...

и я написал следующую функцию для замены адреса на долготу и широту координат этого адреса:

from geopy.geocoders import Nominatim
geo_locator = Nominatim(user_agent="MY_APP_ID")

def get_coordinates(addr):
    location = geo_locator.geocode(addr)
    if location is not None:
        return pd.Series({'lat': location.latitude, 'lon': location.longitude})
    location = geo_locator.geocode(addr.split(',')[0])
    if location is not None:
        return pd.Series({'lat': location.latitude, 'lon': location.longitude})
    return pd.Series({'lat': -1, 'lon': -1})

Затем вызов pandas применяет метод к столбцу адреса и объединяет результат до конца DF вместо столбца адреса:

df = pd.concat([df, df.addr.apply(get_coordinates)], axis=1).drop(['addr'], axis=1)

Однако, поскольку get_coordinates вызывает сторонний API, он не работает:geopy.exc.GeocoderTimedOut: Service timed out

Как отрегулировать запросы, чтобы убедиться, что я получил ответ, прежде чем перейти к следующему значению?

Обновить:
Для дальнейших улучшений, я хотел бы вызывать API только для уникальных значений, т.е. если адресIN,Krishnagiri,635115 появляется в моем DataFrame 20 раз, я хотел бы вызвать его только один раз и применить результаты ко всем 20 вхождениям.

Обновление 2:
Log + Stack trace, для кода @Andrew Lavers:

...
Fetched Gandipet, Khanapur, Rangareddy District, Telangana, 500075, India
Fetched Jaipur Municipal Corporation, Jaipur, Rajasthan, 302015, India
Fetched Chennai, Chennai district, Tamil Nadu, India
Exception from geolocator: Fake exception for testing
Backing off for 1 seconds.
Exception from geolocator: Fake exception for testing
Backing off for 3 seconds.
Fetched None
Traceback (most recent call last):
  File "/usr/local/Cellar/python3/3.6.1/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/geopy/geocoders/base.py", line 344, in _call_geocoder
    page = requester(req, timeout=timeout, **kwargs)
  File "/usr/local/Cellar/python3/3.6.1/Frameworks/Python.framework/Versions/3.6/lib/python3.6/urllib/request.py", line 526, in open
    response = self._open(req, data)
  File "/usr/local/Cellar/python3/3.6.1/Frameworks/Python.framework/Versions/3.6/lib/python3.6/urllib/request.py", line 544, in _open
    '_open', req)
  File "/usr/local/Cellar/python3/3.6.1/Frameworks/Python.framework/Versions/3.6/lib/python3.6/urllib/request.py", line 504, in _call_chain
    result = func(*args)
  File "/usr/local/Cellar/python3/3.6.1/Frameworks/Python.framework/Versions/3.6/lib/python3.6/urllib/request.py", line 1361, in https_open
    context=self._context, check_hostname=self._check_hostname)
  File "/usr/local/Cellar/python3/3.6.1/Frameworks/Python.framework/Versions/3.6/lib/python3.6/urllib/request.py", line 1321, in do_open
    r = h.getresponse()
  File "/usr/local/Cellar/python3/3.6.1/Frameworks/Python.framework/Versions/3.6/lib/python3.6/http/client.py", line 1331, in getresponse
    response.begin()
  File "/usr/local/Cellar/python3/3.6.1/Frameworks/Python.framework/Versions/3.6/lib/python3.6/http/client.py", line 297, in begin
    version, status, rea,son = self._read_status()
  File "/usr/local/Cellar/python3/3.6.1/Frameworks/Python.framework/Versions/3.6/lib/python3.6/http/client.py", line 258, in _read_status
    line = str(self.fp.readline(_MAXLINE + 1), "iso-8859-1")
  File "/usr/local/Cellar/python3/3.6.1/Frameworks/Python.framework/Versions/3.6/lib/python3.6/socket.py", line 586, in readinto
    return self._sock.recv_into(b)
  File "/usr/local/Cellar/python3/3.6.1/Frameworks/Python.framework/Versions/3.6/lib/python3.6/ssl.py", line 1002, in recv_into
    return self.read(nbytes, buffer)
  File "/usr/local/Cellar/python3/3.6.1/Frameworks/Python.framework/Versions/3.6/lib/python3.6/ssl.py", line 865, in read
    return self._sslobj.read(len, buffer)
  File "/usr/local/Cellar/python3/3.6.1/Frameworks/Python.framework/Versions/3.6/lib/python3.6/ssl.py", line 625, in read
    v = self._sslobj.read(len, buffer)
socket.timeout: The read operation timed out

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/...//tmp.py", line 89, in <module>
    df.addr.apply(get_coordinates)
  File "/usr/local/Cellar/python3/3.6.1/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/pandas/core/series.py", line 3194, in apply
    mapped = lib.map_infer(values, f, convert=convert_dtype)
  File "pandas/_libs/src/inference.pyx", line 1472, in pandas._libs.lib.map_infer
  File "/Users/...//tmp.py", line 76, in get_coordinates
    location = geo_locator.geocode(addr.split(',')[0])
  File "/usr/local/Cellar/python3/3.6.1/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/geopy/geocoders/osm.py", line 307, in geocode
    self._call_geocoder(url, timeout=timeout), exactly_one
  File "/usr/local/Cellar/python3/3.6.1/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/geopy/geocoders/base.py", line 371, in _call_geocoder
    raise GeocoderTimedOut('Service timed out')
geopy.exc.GeocoderTimedOut: Service timed out

Process finished with exit code 1