![]() ![]() In our example, we use the prefix ‘ignore’. This allows us to add a prefix – which we specify in the parenthesis – to the nearest neighbor variable generated after the command. In addition to that, we have also added an option of genstub(). geonear city latitude longitude using "industrialcities.dta", ignoreself n(city1 latitude1 longitude1) miles genstub(ignore) If we wish for the distance to the nearest city to be reported in miles, we add a milesoption. geonear city latitude longitude using "industrialcities.dta", ignoreself n(city1 latitude1 longitude1) Calculating Distance in Miles While previously, we had to drop such observation manually, here we simply use the ignoreselfoption to automatically remove them. We do not want such observations (where a city is paired up with itself) in our data. With geodistwe saw that the distance of a city with itself was, rightly, calculated as zero. It creates another variable that shows the distance between the city and its nearest industrial city (the neighbor). This command creates a variable that holds the industrial city names that are nearest to each of the 727 cities. Its parenthesis contain the city, latitude and longitude data from the neighbor file. The option nis a shorter way of writing the neighbors option. This is followed by specifying the dataset that we will use. The first three arguments in the command are the city, latitude and longitude variable names in the master file. To apply the above syntax to the datasets, our command looks like: geonear city latitude longitude using "industrialcities.dta", n(city1 latitude1 longitude1) Find nearest location in stata in kilometres In its parenthesis, we specify the city, latitude and longitude variables from the using file (in the specific order identified in the syntax). ![]() nborfilerefers to the second, neighbor file (aka the ‘using’ file’: industrialcities.dta). the file currently loaded: distance.dta) respectively. ![]() The general syntax of the geonearcommand is as follows: geonear baseid baselat baselon using nborfile, neighbors(nborid nborlat nborlon) īaseid baslat and baselonrefer to the city, latitude and longitude variables in our masterfile (i.e. We start by using the first of the two datasets: use "distance.dta",clearįor each of the 727 cities, we wish to know which among the four industrial cities is the nearest to them. This is an importance and necessary feature of the two datasets. ![]() For example city names are stored in a variable called ‘city’ in distance.dta but ‘city1’ in industrialcities.dta. The names of the variables in both files different, even though they represent the same information. This item may be available elsewhere in EconPapers: Search for items with the same has longitude and latitude data on four US industrial cities. Windows users should not attempt to download these files with a web browser.Ĭitations: View citations in EconPapers (19) Track citations by RSS feed The module is made available under terms of the GPL v3 (). Note: This module should be installed from within Stata by typing "ssc install geodist". Keywords: geodetic geodesic Vincenty great-circle ellipsoid distance (search for similar items in EconPapers) geodist can also calculate great-circle distances using the haversine formula. By default, geodist implements Vincenty's (1975) formula to calculate distances on a reference ellipsoid. Geodist calculates geographical distances by measuring the length of the shortest path between two points along the surface of a mathematical model of the earth. Statistical Software Components from Boston College Department of Economics GEODIST: Stata module to compute geographical distances ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |