Stata: How to execute the georoute command for values of each variable

Question

Is it possible to run the command georoute for multiple values at the same time? I'm running the following line:

 georoutei, hereid(BfSfwSlKMCPHj5WbVJ1g) herecode(bFw1UDZM3Zgc4QM8lyknVg) startxy(46.1761413,6.1393099) endxy(46.99382,6.94049) km

However, I have more than 1000 values (coordinates) as a start and end point. I'd like to tell Stata something like replace startxy and endxy for each value of the variables. So, I'm trying to do this across a loop but it doesn't work. Can someone help me?

I'm trying to do this:

clear all

set obs 1000
set seed 1254
ssc install georoutei

gen x1 = 45 + int(40+1)*uniform() 
gen xf = 46+ int(46+1)*runiform()
gen y1 = 6 + int(6+1)*runiform()
gen yf = 7 + int(7+1)*runiform()

georoutei, hereid(tKNXdBlaC1UoKDWAiJ4i) herecode(4SQsFZphiBfXL4xWa7SPgg) 
startxy(3.4372222,-76.33376) endxy(3.7231,-76.525902) km

forvalue i=1(1)1000{
levelsof x1, local(startx)
levelsof xf, local(endf) 
levelsof y1, local(starty)
levelsof yf, local(endy)
    georoutei, hereid(tKNXdBlaC1UoKDWAiJ4i) herecode(4SQsFZphiBfXL4xWa7SPgg) 
    startxy(`startx',`starty') endxy(`endx',`endy')km
}

Then I need to record the travel distance in a matrix or something like this to have a new variable with this information. I'm looking to save a little time instead of having to run a bunch of lines for each pair of coordinates.

Thank you!

Hello Matthew, I've edited the post, maybe the question can be easier to understand. — Carolina Bermudez

Matthew White Matthew White · Accepted Answer · 2017-06-29T15:48:44

The issue is that each iteration of the loop is running the same levelsof command: there is no if or in qualifier specified to levelsof, so for each iteration of the loop, levelsof is running for all observations.

Instead of levelsof, I recommend using explicit subscripting. You can read more about it here and here. For example:

generate distance = .
forvalues i = 1/100 {
    local startx = x1[`i']
    local endf = xf[`i']
    local starty = y1[`i']
    local endy = yf[`i']
    georoutei, hereid(tKNXdBlaC1UoKDWAiJ4i) herecode(4SQsFZphiBfXL4xWa7SPgg) startxy(`starty',`startx') endxy(`endy',`endx') km
    replace distance = r(dist) in `i'
}

Definitely a good idea to turn this into a loop!

Stata: How to execute the georoute command for values of each variable

1 Answers