mongodb geospatial methods ( using PyMongo in R )

Source: R/utils.R

mongodb geospatial methods ( using PyMongo in R )

mongodb geospatial methods ( using PyMongo in R )

# init <- geomongo$new(host = 'localhost', port = 27017,

       #                      tz_aware = FALSE, connect = TRUE, ...)

Details

See the reference link for more details on the ellipsis (...) concerning the additional parameters of the MongoClient()

the geomongo$new method initializes the MongoClient

the getClient method returns a "pymongo.mongo_client.MongoClient" object

the read_mongo_bson method allows the user to read a file/string using the bson.json_util module, which loads MongoDB Extended JSON data ( SEE https://stackoverflow.com/questions/42089045/bson-errors-invaliddocument-key-oid-must-not-start-with-trying-to-insert )

the geoInsert method allows the user to import data to a mongo-db from a folder, file or list

the geoQuery method allows the user to perform geospatial queries using one of the find, aggregate or command methods

For spherical query operators to function properly, you must convert distances to radians, and convert from radians to the distances units used by your application.

To convert distance to radians: divide the distance by the radius of the sphere (e.g. the Earth) in the same units as the distance measurement. To convert radians to distance: multiply the radian measure by the radius of the sphere (e.g. the Earth) in the units system that you want to convert the distance to.

The equatorial radius of the Earth is approximately 3,963.2 miles or 6,378.1 kilometers.

If specifying latitude and longitude coordinates, list the longitude first and then latitude:

Valid longitude values are between -180 and 180, both inclusive. Valid latitude values are between -90 and 90 (both inclusive).

Methods

geomongo$new(host = 'localhost', port = 27017, tz_aware = FALSE, connect = TRUE, ...)

--------------

getClient()

--------------

read_mongo_bson(FILE = NULL, STR = NULL)

--------------

geoInsert(DATA = NULL, TYPE_DATA = NULL, COLLECTION = NULL, GEOMETRY_NAME = NULL, read_method = "geojsonR")

--------------

geoQuery(QUERY = NULL, METHOD = NULL, COLLECTION = NULL, DATABASE = NULL, GEOMETRY_NAME = NULL, TO_LIST = FALSE)

References

https://github.com/mongodb/mongo-python-driver, https://docs.mongodb.com/manual/tutorial/calculate-distances-using-spherical-geometry-with-2d-geospatial-indexes/

Methods

Public methods

Method new()

Usage

geomongo$new(
  host = "localhost",
  port = 27017,
  tz_aware = FALSE,
  connect = TRUE,
  ...
)

Arguments

host

(optional) hostname or IP address or Unix domain socket path of a single mongod or mongos instance to connect to, or a mongodb URI, or a list of hostnames / mongodb URIs. See the reference link for more information.

port

(optional) port number on which to connect

tz_aware

(optional) if TRUE, datetime instances returned as values in a document by this MongoClient will be timezone aware (otherwise they will be naive)

connect

(optional) if TRUE (the default), immediately begin connecting to MongoDB in the background. Otherwise connect on the first operation

Method getClient()

Usage

geomongo$getClient()

Method read_mongo_bson()

Usage

geomongo$read_mongo_bson(FILE = NULL, STR = NULL)

Arguments

FILE

a character string specifying a valid path to a file ( applies to read_mongo_bson method )

STR

a character string ( applies to read_mongo_bson method )

Method geoInsert()

Usage

geomongo$geoInsert(
  DATA = NULL,
  TYPE_DATA = NULL,
  COLLECTION = NULL,
  GEOMETRY_NAME = NULL,
  read_method = "geojsonR"
)

Arguments

DATA

a valid path to a file/folder or a list ( applies to geoInsert method )

TYPE_DATA

a character string. One of 'folder', 'file', 'dict_one' (takes as input a list or a character string) or 'dict_many' (takes as input a list or a character string vector) ( applies to geoInsert method )

COLLECTION

a pymongo.collection.Collection object ( applies to geoInsert and geoQuery methods )

GEOMETRY_NAME

a character string specifying the name of the geometry object, as it appears in the file/string ( applies to geoInsert and geoQuery methods )

read_method

a character string specifying the method to use to read the data. Either using the "geojsonR" (package) or the "mongo_bson" utility function ( applies to geoInsert method )

Method geoQuery()

Usage

geomongo$geoQuery(
  QUERY = NULL,
  METHOD = NULL,
  COLLECTION = NULL,
  DATABASE = NULL,
  GEOMETRY_NAME = NULL,
  TO_LIST = FALSE
)

Arguments

QUERY

a named list specifying the query to use in mongodb ( applies to geoQuery method )

METHOD

a character string specifying the method to use to perform geospatial queries in mongodb. One of "find", "aggregate" OR "command" ( applies to geoQuery method )

COLLECTION

a pymongo.collection.Collection object ( applies to geoInsert and geoQuery methods )

DATABASE

a "pymongo.database.Database" object ( applies to geoQuery method )

GEOMETRY_NAME

a character string specifying the name of the geometry object, as it appears in the file/string ( applies to geoInsert and geoQuery methods )

TO_LIST

either TRUE or FALSE. If TRUE then the output of the geoQuery method will be a list, otherwise a data.table (matrix) object ( applies to geoQuery method )

Method clone()

The objects of this class are cloneable with this method.

Usage

geomongo$clone(deep = FALSE)

Arguments

deep

Whether to make a deep clone.

Examples


if (FALSE) {

library(GeoMongo)

init = geomongo$new()

getter_client = init$getClient()

init_db = getter_client$get_database("example_db")

init_col = init_db$get_collection("example_collection")

#--------------------------
# geonear using 'aggregate'
#--------------------------

query_geonear = list('$geoNear' = list(near = list(type = "Point", coordinates = c(-122.5, 37.1)),

                     distanceField = "distance", maxDistance = 900 * 1609.34,

                     distanceMultiplier = 1 / 1609.34, spherical = TRUE))


init$geoQuery(QUERY = query_geonear, METHOD = "aggregate", COLLECTION = init_col,

              DATABASE = init_db, GEOMETRY_NAME = "location", TO_LIST = FALSE)
}