Related
I am using the gis extension of Netlogo and am trying to calculate distances between agents in km.
With gis:envelope-of I can get agent's positions in degree (!) latitude and longitude, so I want to use the Haversine formula to calculate distances. The projection of my underlying GIS-shapefile is WGS 84.
What I've written for two exemplary points is the following:
to haversine
let lata 31.8930795682288
let longa 36.0898369172224
let latb 31.9964498913126
let longb 36.0318329821497
let rad (pi / 180)
let result acos (cos (rad * lata) * cos(rad * (latb )) + sin ( rad * (lata) )* sin(rad * (latb)) * cos(rad * (longa - longb))) * 6371
print result
end
It yields a distance of 11.5 km, while the same formula applied in excel (using the RADIANS-formula instead of "rad") leaves me with 12.73 km, a number that this website http://www.movable-type.co.uk/scripts/latlong.html confirms.
Any idea what I'm doing wrong here? Thanks in advance.
The formula that computes result is not correct. It looks like you reversed sin and cos. Use
let result acos(sin(rad * lata) * sin(rad * latb) + cos(rad * lata) * cos(rad * latb) * cos(rad * (longa - longb))) * 6371
Also, according to the docs that I've read (e.g. cos and acos), the netlogo trig functions use degrees, so the calculation should be
let result rad * acos(sin(lata) * sin(latb) + cos(lata) * cos(latb) * cos(longa - longb)) * 6371
I found this formula and it works, however what i trying to do is to give ability to filter by distance from his ZIP code.
I found formula that calculates distance between two latitude and longitude coordinates.
(3956 * ACOS(COS(RADIANS(start_lat)) * COS(RADIANS(end_lat)) * COS(RADIANS(end_lon) - RADIANS(start_lon)) + SIN(RADIANS(start_lat)) * SIN(RADIANS(end_lat))))
I have filter on page that sends following info
$_POST["start_latitude"] = 34.023179;
$_POST["start_longitude"] = -118.303965;
$_POST["max_distance"] = 50;
If i do
SELECT (3956 * ACOS(COS(RADIANS({$_POST["start_latitude"]})) * COS(RADIANS(34.018626))
* COS(RADIANS(-118.249978) - RADIANS({$_POST["start_longitude"]}))
+ SIN(RADIANS({$_POST["start_latitude"]})) * SIN(RADIANS(34.018626))))
Will output distance as number of miles 4 miles in this case.
How can i convert this formula for my goal to find places no longer than say 50 miles from coordinates entered? I know all need to be done is change of places in formula, but i am not good with school math.
SELECT place_name FROM places
WHERE place_latitude = ? AND place_longitude = ?
EDIT:
I have places table where i got 1000 records in format
id place_name latitude longitude
1 xxx 432423 -43432
2 yyy 523452 -54353
3 zzz 553453 -53422
etc.
So the formula has to do something like
SELECT place_name FROM places
(CALCULATE each place distance from
$_POST["start_latitude"] and $_POST["start_longitude"]
and select only ones that) < 50
Put the distance formula into the WHERE clause:
SELECT place_name
FROM places
WHERE (3956 * ACOS(COS(RADIANS(:start_latitude)) * COS(RADIANS(latitude)) * COS(RADIANS(-longitude) - RADIANS(:start_longitude)) + SIN(RADIANS(:start_latitude)) * SIN(RADIANS(latitude))))
< :max_distance
This resouce and web service usefull, check it:
http://www.codebump.com/services/PlaceLookup.asmx
function calc_distance($point1, $point2)
{
$radius = 3958; // Earth's radius (miles)
$deg_per_rad = 57.29578; // Number of degrees/radian (for conversion)
$distance = ($radius * pi() * sqrt(
($point1['lat'] - $point2['lat'])
* ($point1['lat'] - $point2['lat'])
+ cos($point1['lat'] / $deg_per_rad) // Convert these to
* cos($point2['lat'] / $deg_per_rad) // radians for cos()
* ($point1['long'] - $point2['long'])
* ($point1['long'] - $point2['long'])
) / 180);
return $distance; // Returned using the units used for $radius.
}
EDIT
Check the page :
http://www.mssqltips.com/sqlservertip/2690/calculate-the-geographical-distance-between-two-cities-in-sql-server/
--
DECLARE #98001 GEOGRAPHY;
DECLARE #Patzip GEOGRAPHY;
SELECT #98001 = Coordinates FROM ZipCodeLKUP INNER JOIN
Facility ON ZipCodeLKUP.ZipCode = Facility.ZipCode
Where Facility.ZipCode=98001
SELECT #Patzip = Coordinates FROM ZipCodeLKUP INNER JOIN
HIDIMV_year ON ZipCodeLKUP.ZipCode = HIDIMV_year .Patzip
where PATZIP in ('98001', '98466','97202')
SELECT #98001.STDistance(#Patzip)/1000 AS [Distance in KM]
Locked. This question and its answers are locked because the question is off-topic but has historical significance. It is not currently accepting new answers or interactions.
What's more appropriate than a Spiral for Easter Code Golf sessions? Well, I guess almost anything.
The Challenge
The shortest code by character count to display a nice ASCII Spiral made of asterisks ('*').
Input is a single number, R, that will be the x-size of the Spiral. The other dimension (y) is always R-2. The program can assume R to be always odd and >= 5.
Some examples:
Input
7
Output
*******
* *
* *** *
* * *
***** *
Input
9
Output
*********
* *
* ***** *
* * * *
* *** * *
* * *
******* *
Input
11
Output
***********
* *
* ******* *
* * * *
* * *** * *
* * * * *
* ***** * *
* * *
********* *
Code count includes input/output (i.e., full program).
Any language is permitted.
My easily beatable 303 chars long Python example:
import sys;
d=int(sys.argv[1]);
a=[d*[' '] for i in range(d-2)];
r=[0,-1,0,1];
x=d-1;y=x-2;z=0;pz=d-2;v=2;
while d>2:
while v>0:
while pz>0:
a[y][x]='*';
pz-=1;
if pz>0:
x+=r[z];
y+=r[(z+1)%4];
z=(z+1)%4; pz=d; v-=1;
v=2;d-=2;pz=d;
for w in a:
print ''.join(w);
Now, enter the Spiral...
Python (2.6): 156 chars
r=input()
def p(r,s):x=(i+1)/2;print "* "*x+("*" if~i%2 else" ")*(r-4*x)+" *"*x+s
for i in range(r/2):p(r,"")
for i in range((r-1)/2-1)[::-1]:p(r-2," *")
Thanks for the comments. I've removed extraneous whitespace and used input(). I still prefer a program that takes its argument on the command-line, so here's a version still using sys.argv at 176 chars:
import sys
r=int(sys.argv[1])
def p(r,s):x=(i+1)/2;print "* "*x+("*" if~i%2 else" ")*(r-4*x)+" *"*x+s
for i in range(r/2):p(r,"")
for i in range((r-1)/2-1)[::-1]:p(r-2," *")
Explanation
Take the spiral and chop it in two almost-equal parts, top and bottom, with the top one row bigger than the bottom:
***********
* *
* ******* *
* * * *
* * *** * *
* * * * *
* ***** * *
* * *
********* *
Observe how the top part is nice and symmetrical. Observe how the bottom part has a vertical line down the right side, but is otherwise much like the top. Note the pattern in every second row at the top: an increasing number of stars on each side. Note that each intervening row is exactly the saw as the one before except it fills in the middle area with stars.
The function p(r,s) prints out the ith line of the top part of the spiral of width r and sticks the suffix s on the end. Note that i is a global variable, even though it might not be obvious! When i is even it fills the middle of the row with spaces, otherwise with stars. (The ~i%2 was a nasty way to get the effect of i%2==0, but is actually not necessary at all because I should have simply swapped the "*" and the " ".) We first draw the top rows of the spiral with increasing i, then we draw the bottom rows with decreasing i. We lower r by 2 and suffix " *" to get the column of stars on the right.
Java
328 characters
class S{
public static void main(String[]a){
int n=Integer.parseInt(a[0]),i=n*(n-2)/2-1,j=0,t=2,k;
char[]c=new char[n*n];
java.util.Arrays.fill(c,' ');
int[]d={1,n,-1,-n};
if(n/2%2==0){j=2;i+=1+n;}
c[i]='*';
while(t<n){
for(k=0;k<t;k++)c[i+=d[j]]='*';
j=(j+1)%4;
if(j%2==0)t+=2;
}
for(i=0;i<n-2;i++)System.out.println(new String(c,i*n,n));
}
}
As little as 1/6 more than Python seems not too bad ;)
Here's the same with proper indentation:
class S {
public static void main(String[] a) {
int n = Integer.parseInt(a[0]), i = n * (n - 2) / 2 - 1, j = 0, t = 2, k;
char[] c = new char[n * n];
java.util.Arrays.fill(c, ' ');
int[] d = { 1, n, -1, -n };
if (n / 2 % 2 == 0) {
j = 2;
i += 1 + n;
}
c[i] = '*';
while (t < n) {
for (k = 0; k < t; k++)
c[i += d[j]] = '*';
j = (j + 1) % 4;
if (j % 2 == 0)
t += 2;
}
for (i = 0; i < n - 2; i++)
System.out.println(new String(c, i * n, n));
}
}
F#, 267 chars
A lot of answers are starting with blanks and adding *s, but I think it may be easier to start with a starfield and add whitespace.
let n=int(System.Console.ReadLine())-2
let mutable x,y,d,A=n,n,[|1;0;-1;0|],
Array.init(n)(fun _->System.Text.StringBuilder(String.replicate(n+2)"*"))
for i=1 to n do for j=1 to(n-i+1)-i%2 do x<-x+d.[i%4];y<-y+d.[(i+1)%4];A.[y].[x]<-' '
Seq.iter(printfn"%O")A
For those looking for insight into how I golf, I happened to save a lot of progress along the way, which I present here with commentary. Not every program is quite right, but they're all honing in on a shorter solution.
First off, I looked for a pattern of how to paint the white:
*********
* *
* ***** *
* * * *
* *** * *
* * *
******* *
*********
*6543216*
*1*****5*
*2*212*4*
*3***1*3*
*41234*2*
*******1*
***********
* *
* ******* *
* * * *
* * *** * *
* * * * *
* ***** * *
* * *
********* *
***********
*876543218*
*1*******7*
*2*43214*6*
*3*1***3*5*
*4*212*2*4*
*5*****1*3*
*6123456*2*
*********1*
Ok, I see it. First program:
let Main() =
let n=int(System.Console.ReadLine())
let A=Array2D.create(n-2)n '*'
let mutable x,y,z,i=n-2,n-2,0,n-2
let d=[|0,-1;-1,0;0,1;1,0|] // TODO
while i>0 do
for j in 1..i-(if i%2=1 then 1 else 0)do
x<-x+fst d.[z]
y<-y+snd d.[z]
A.[y,x]<-'0'+char j
z<-(z+1)%4
i<-i-1
printfn"%A"A
Main()
I know that d, the tuple-array of (x,y)-diffs-modulo-4 can later be reduced by x and y both indexing into different portions of the same int-array, hence the TODO. The rest is straightforward based on the visual insight into 'whitespace painting'. I'm printing a 2D array, which is not right, need an array of strings, so:
let n=int(System.Console.ReadLine())
let s=String.replicate n "*"
let A=Array.init(n-2)(fun _->System.Text.StringBuilder(s))
let mutable x,y,z,i=n-2,n-2,0,n-2
let d=[|0,-1;-1,0;0,1;1,0|]
while i>0 do
for j in 1..i-(if i%2=1 then 1 else 0)do
x<-x+fst d.[z]
y<-y+snd d.[z]
A.[y].[x]<-' '
z<-(z+1)%4
i<-i-1
for i in 0..n-3 do
printfn"%O"A.[i]
Ok, now let's change the array of tuples into an array of int:
let n=int(System.Console.ReadLine())-2
let mutable x,y,z,i,d=n,n,0,n,[|0;-1;0;1;0|]
let A=Array.init(n)(fun _->System.Text.StringBuilder(String.replicate(n+2)"*"))
while i>0 do
for j in 1..i-i%2 do x<-x+d.[z];y<-y+d.[z+1];A.[y].[x]<-' '
z<-(z+1)%4;i<-i-1
A|>Seq.iter(printfn"%O")
The let for A can be part of the previous line. And z and i are mostly redundant, I can compute one in terms of the other.
let n=int(System.Console.ReadLine())-2
let mutable x,y,d,A=n,n,[|0;-1;0;1|],
Array.init(n)(fun _->System.Text.StringBuilder(String.replicate(n+2)"*"))
for i=n downto 1 do for j in 1..i-i%2 do x<-x+d.[(n-i)%4];y<-y+d.[(n-i+1)%4];A.[y].[x]<-' '
Seq.iter(printfn"%O")A
downto is long, re-do the math so I can go (up) to in the loop.
let n=int(System.Console.ReadLine())-2
let mutable x,y,d,A=n,n,[|1;0;-1;0|],
Array.init(n)(fun _->System.Text.StringBuilder(String.replicate(n+2)"*"))
for i=1 to n do for j in 1..(n-i+1)-i%2 do x<-x+d.[i%4];y<-y+d.[(i+1)%4];A.[y].[x]<-' '
Seq.iter(printfn"%O")A
A little more tightening yields the final solution.
Python : 238 - 221 - 209 characters
All comments welcome:
d=input();r=range
a=[[' ']*d for i in r(d-2)]
x=y=d/4*2
s=d%4-2
for e in r(3,d+1,2):
for j in r(y,y+s*e-s,s):a[x][j]='*';y+=s
for j in r(x,x+s*e-(e==d)-s,s):a[j][y]='*';x+=s
s=-s
for l in a:print''.join(l)
Groovy, 373 295 257 243 chars
Tried a recursive approach that builds up squares starting from the most extern one going inside.. I used Groovy.
*********
*********
*********
*********
*********
*********
******* *
*********
* *
* *
* *
* *
* * *
******* *
*********
* *
* ***** *
* ***** *
* *** * *
* * *
******* *
*********
* *
* ***** *
* * * *
* *** * *
* * *
******* *
and so on..
r=args[0] as int;o=r+1;c='*'
t=new StringBuffer('\n'*(r*r-r-2))
e(r,0)
def y(){c=c==' '?'*':' '}
def e(s,p){if (s==3)t[o*p+p..o*p+p+2]=c*s else{l=o*(p+s-3)+p+s-2;(p+0..<p+s-2).each{t[o*it+p..<o*it+p+s]=c*s};y();t[l..l]=c;e(s-2,p+1)}}
println t
readable one:
r=args[0] as int;o=r+1;c='*'
t=new StringBuffer('\n'*(r*r-r-2))
e(r,0)
def y(){c=c==' '?'*':' '}
def e(s,p){
if (s==3)
t[o*p+p..o*p+p+2]=c*s
else{
l=o*(p+s-3)+p+s-2
(p+0..<p+s-2).each{
t[o*it+p..<o*it+p+s]=c*s}
y()
t[l..l]=c
e(s-2,p+1)
}
}
println t
EDIT: improved by just filling squares and then overriding them (check new example): so I avoided to fill just the edge of the rect but the whole one.
Ruby, 237 chars
I'm new to code golf, so I'm way off the mark, but I figured I'd give it a shot.
x=ARGV[0].to_i
y=x-2
s,h,j,g=' ',x-1,y-1,Array.new(y){Array.new(x,'*')}
(1..x/2+2).step(2){|d|(d..y-d).each{|i|g[i][h-d]=s}
(d..h-d).each{|i|g[d][i]=s}
(d..j-d).each{|i|g[i][d]=s}
(d..h-d-2).each{|i|g[j-d][i]=s}}
g.each{|r|print r;puts}
Long version
Java, 265 250 245 240 chars
Rather than preallocating a rectangular buffer and filling it in, I just loop over x/y coordinates and output '*' or ' ' for the current position. For this, we need an algorithm which can evaluate arbitrary points for whether they're on the spiral. The algorithm I used is based on the observation that the spiral is equivalent to a collection of concentric squares, with the exception of a set of positions which all happen along a particular diagonal; these positions require a correction (they must be inverted).
The somewhat readable version:
public class Spr2 {
public static void main(String[] args) {
int n = Integer.parseInt(args[0]);
int cy = (n - 5) / 4 * 2 + 1;
int cx = cy + 2;
for (int y = n - 3; y >= 0; y--) {
for (int x = 0; x < n; x++) {
int dx = cx - x;
int dy = cy - y;
int adx = Math.abs(dx);
int ady = Math.abs(dy);
boolean c = (dx > 0 && dx == dy + 1);
boolean b = ((adx % 2 == 1 && ady <= adx) || (ady % 2 == 1 && adx <= ady)) ^ c;
System.out.print(b ? '*' : ' ');
}
System.out.println();
}
}
}
A brief explanation for the above:
cx,cy = center
dx,dy = delta from center
adx,ady = abs(delta from center)
c = correction factor (whether to invert)
b = the evaluation
Optimized down. 265 chars:
public class S{
public static void main(String[]a){
int n=Integer.parseInt(a[0]),c=(n-5)/4*2+1,d=c+2,e,f,g,h,x,y;
for(y=0;y<n-2;y++){
for(x=0;x<=n;x++){
e=d-x;f=c-y;g=e>0?e:-e;h=f>0?f:-f;
System.out.print(x==n?'\n':(g%2==1&&h<=g||h%2==1&&g<=h)^(e>0&&e==f+1)?'*':' ');
}}}}
Updated. Now down to 250 chars:
class S{
public static void main(String[]a){
int n=Integer.parseInt(a[0]),c=(n-5)/4*2+1,d=c+2,g,h,x,y;
for(y=-c;y<n-2-c;y++){
for(x=-d;x<=n-d;x++){
g=x>0?x:-x;h=y>0?y:-y;
System.out.print(x==n-d?'\n':(g%2==1&&h<=g||h%2==1&&g<=h)^(x<0&&x==y-1)?'*':' ');
}}}}
Shaved just a few more characters. 245 chars:
class S{
public static void main(String[]a){
int n=Integer.parseInt(a[0]),c=(n-5)/4*2+1,d=c+2,g,h,x,y=-c;
for(;y<n-2-c;y++){
for(x=-d;x<=n-d;x++){
g=x>0?x:-x;h=y>0?y:-y;
System.out.print(x==n-d?'\n':(g%2==1&h<=g|h%2==1&g<=h)^(x<0&x==y-1)?'*':' ');
}}}}
Shaved just a few more characters. 240 chars:
class S{
public static void main(String[]a){
int n=Byte.decode(a[0]),c=(n-5)/4*2+1,d=c+2,g,h,x,y=-c;
for(;y<n-2-c;y++){
for(x=-d;x<=n-d;x++){
g=x>0?x:-x;h=y>0?y:-y;
System.out.print(x==n-d?'\n':(g%2==1&h<=g|h%2==1&g<=h)^(x<0&x==y-1)?'*':' ');
}}}}
OCaml, 299 chars
Here is a solution in OCaml, not the shortest but I believe quite readable.
It only uses string manipulations using the fact the you can build a spiral by mirroring the previous one.
Let's say you start at with n = 5:
55555
5 5
555 5
Now with n = 7:
7777777
7 7
5 555 7
5 5 7
55555 7
Did you see where all the 5's went ?
Here is the unobfuscated code using only the limited library provided with OCaml:
(* The standard library lacks a function to reverse a string *)
let rev s =
let n = String.length s - 1 in
let r = String.create (n + 1) in
for i = 0 to n do
r.[i] <- s.[n - i]
done;
r
;;
let rec f n =
if n = 5 then
[
"*****";
"* *";
"*** *"
]
else
[
String.make n '*';
"*" ^ (String.make (n - 2) ' ') ^ "*"
] # (
List.rev_map (fun s -> (rev s) ^ " *") (f (n - 2))
)
;;
let p n =
List.iter print_endline (f n)
;;
let () = p (read_int ());;
Here is the obfuscated version which is 299 characters long:
open String
let rev s=
let n=length s-1 in
let r=create(n+1)in
for i=0 to n do r.[i]<-s.[n-i]done;r
let rec f n=
if n=5 then["*****";"* *";"*** *"]else
[make n '*';"*"^(make (n-2) ' ')^"*"]
#(List.rev_map(fun s->(rev s)^" *")(f(n-2)));;
List.iter print_endline (f(read_int ()))
C#, 292 262 255 chars
Simple approach: draw the spiral line by line from the outside in.
using C=System.Console;class P{static void Main(string[]a){int A=
1,d=1,X=int.Parse(a[0]),Y=X-2,l=X,t=0,i,z;while(l>2){d*=A=-A;l=l<
4?4:l;for(i=1;i<(A<0?l-2:l);i++){C.SetCursorPosition(X,Y);C.Write
("*");z=A<0?Y+=d:X+=d;}if(t++>1||l<5){l-=2;t=1;}}C.Read();}}
Ruby (1.9.2) — 126
f=->s{s<0?[]:(z=?**s;[" "*s]+(s<2?[]:[z]+f[s-4]<<?*.rjust(s))).map{|i|"* #{i} *"}<<z+"** *"}
s=gets.to_i;puts [?**s]+f[s-4]
Perl, where are you? )
I have latitude and longitude and I want to pull the record from the database, which has nearest latitude and longitude by the distance, if that distance gets longer than specified one, then don't retrieve it.
Table structure:
id
latitude
longitude
place name
city
country
state
zip
sealevel
SELECT latitude, longitude, SQRT(
POW(69.1 * (latitude - [startlat]), 2) +
POW(69.1 * ([startlng] - longitude) * COS(latitude / 57.3), 2)) AS distance
FROM TableName HAVING distance < 25 ORDER BY distance;
where [starlat] and [startlng] is the position where to start measuring the distance.
Google's solution:
Creating the Table
When you create the MySQL table, you want to pay particular attention to the lat and lng attributes. With the current zoom capabilities of Google Maps, you should only need 6 digits of precision after the decimal. To keep the storage space required for your table at a minimum, you can specify that the lat and lng attributes are floats of size (10,6). That will let the fields store 6 digits after the decimal, plus up to 4 digits before the decimal, e.g. -123.456789 degrees. Your table should also have an id attribute to serve as the primary key.
CREATE TABLE `markers` (
`id` INT NOT NULL AUTO_INCREMENT PRIMARY KEY ,
`name` VARCHAR( 60 ) NOT NULL ,
`address` VARCHAR( 80 ) NOT NULL ,
`lat` FLOAT( 10, 6 ) NOT NULL ,
`lng` FLOAT( 10, 6 ) NOT NULL
) ENGINE = MYISAM ;
Populating the Table
After creating the table, it's time to populate it with data. The sample data provided below is for about 180 pizzarias scattered across the United States. In phpMyAdmin, you can use the IMPORT tab to import various file formats, including CSV (comma-separated values). Microsoft Excel and Google Spreadsheets both export to CSV format, so you can easily transfer data from spreadsheets to MySQL tables through exporting/importing CSV files.
INSERT INTO `markers` (`name`, `address`, `lat`, `lng`) VALUES ('Frankie Johnnie & Luigo Too','939 W El Camino Real, Mountain View, CA','37.386339','-122.085823');
INSERT INTO `markers` (`name`, `address`, `lat`, `lng`) VALUES ('Amici\'s East Coast Pizzeria','790 Castro St, Mountain View, CA','37.38714','-122.083235');
INSERT INTO `markers` (`name`, `address`, `lat`, `lng`) VALUES ('Kapp\'s Pizza Bar & Grill','191 Castro St, Mountain View, CA','37.393885','-122.078916');
INSERT INTO `markers` (`name`, `address`, `lat`, `lng`) VALUES ('Round Table Pizza: Mountain View','570 N Shoreline Blvd, Mountain View, CA','37.402653','-122.079354');
INSERT INTO `markers` (`name`, `address`, `lat`, `lng`) VALUES ('Tony & Alba\'s Pizza & Pasta','619 Escuela Ave, Mountain View, CA','37.394011','-122.095528');
INSERT INTO `markers` (`name`, `address`, `lat`, `lng`) VALUES ('Oregano\'s Wood-Fired Pizza','4546 El Camino Real, Los Altos, CA','37.401724','-122.114646');
Finding Locations with MySQL
To find locations in your markers table that are within a certain radius distance of a given latitude/longitude, you can use a SELECT statement based on the Haversine formula. The Haversine formula is used generally for computing great-circle distances between two pairs of coordinates on a sphere. An in-depth mathemetical explanation is given by Wikipedia and a good discussion of the formula as it relates to programming is on Movable Type's site.
Here's the SQL statement that will find the closest 20 locations that are within a radius of 25 miles to the 37, -122 coordinate. It calculates the distance based on the latitude/longitude of that row and the target latitude/longitude, and then asks for only rows where the distance value is less than 25, orders the whole query by distance, and limits it to 20 results. To search by kilometers instead of miles, replace 3959 with 6371.
SELECT
id,
(
3959 *
acos(cos(radians(37)) *
cos(radians(lat)) *
cos(radians(lng) -
radians(-122)) +
sin(radians(37)) *
sin(radians(lat )))
) AS distance
FROM markers
HAVING distance < 28
ORDER BY distance LIMIT 0, 20;
This one is to find latitudes and longitudes in a distance less than 28 miles.
Another one is to find them in a distance between 28 and 29 miles:
SELECT
id,
(
3959 *
acos(cos(radians(37)) *
cos(radians(lat)) *
cos(radians(lng) -
radians(-122)) +
sin(radians(37)) *
sin(radians(lat )))
) AS distance
FROM markers
HAVING distance < 29 and distance > 28
ORDER BY distance LIMIT 0, 20;
https://developers.google.com/maps/articles/phpsqlsearch_v3#creating-the-map
The original answers to the question are good, but newer versions of mysql (MySQL 5.7.6 on) support geo queries, so you can now use built in functionality rather than doing complex queries.
You can now do something like:
select *, ST_Distance_Sphere( point ('input_longitude', 'input_latitude'),
point(longitude, latitude)) * .000621371192
as `distance_in_miles`
from `TableName`
having `distance_in_miles` <= 'input_max_distance'
order by `distance_in_miles` asc
The results are returned in meters. So if you want in KM simply use .001 instead of .000621371192 (which is for miles).
MySql docs are here
Here is my full solution implemented in PHP.
This solution uses the Haversine formula as presented in http://www.scribd.com/doc/2569355/Geo-Distance-Search-with-MySQL.
It should be noted that the Haversine formula experiences weaknesses around the poles. This answer shows how to implement the vincenty Great Circle Distance formula to get around this, however I chose to just use Haversine because it's good enough for my purposes.
I'm storing latitude as DECIMAL(10,8) and longitude as DECIMAL(11,8). Hopefully this helps!
showClosest.php
<?PHP
/**
* Use the Haversine Formula to display the 100 closest matches to $origLat, $origLon
* Only search the MySQL table $tableName for matches within a 10 mile ($dist) radius.
*/
include("./assets/db/db.php"); // Include database connection function
$db = new database(); // Initiate a new MySQL connection
$tableName = "db.table";
$origLat = 42.1365;
$origLon = -71.7559;
$dist = 10; // This is the maximum distance (in miles) away from $origLat, $origLon in which to search
$query = "SELECT name, latitude, longitude, 3956 * 2 *
ASIN(SQRT( POWER(SIN(($origLat - latitude)*pi()/180/2),2)
+COS($origLat*pi()/180 )*COS(latitude*pi()/180)
*POWER(SIN(($origLon-longitude)*pi()/180/2),2)))
as distance FROM $tableName WHERE
longitude between ($origLon-$dist/cos(radians($origLat))*69)
and ($origLon+$dist/cos(radians($origLat))*69)
and latitude between ($origLat-($dist/69))
and ($origLat+($dist/69))
having distance < $dist ORDER BY distance limit 100";
$result = mysql_query($query) or die(mysql_error());
while($row = mysql_fetch_assoc($result)) {
echo $row['name']." > ".$row['distance']."<BR>";
}
mysql_close($db);
?>
./assets/db/db.php
<?PHP
/**
* Class to initiate a new MySQL connection based on $dbInfo settings found in dbSettings.php
*
* #example $db = new database(); // Initiate a new database connection
* #example mysql_close($db); // close the connection
*/
class database{
protected $databaseLink;
function __construct(){
include "dbSettings.php";
$this->database = $dbInfo['host'];
$this->mysql_user = $dbInfo['user'];
$this->mysql_pass = $dbInfo['pass'];
$this->openConnection();
return $this->get_link();
}
function openConnection(){
$this->databaseLink = mysql_connect($this->database, $this->mysql_user, $this->mysql_pass);
}
function get_link(){
return $this->databaseLink;
}
}
?>
./assets/db/dbSettings.php
<?php
$dbInfo = array(
'host' => "localhost",
'user' => "root",
'pass' => "password"
);
?>
It may be possible to increase performance by using a MySQL stored procedure as suggested by the "Geo-Distance-Search-with-MySQL" article posted above.
I have a database of ~17,000 places and the query execution time is 0.054 seconds.
Just in case you are lazy like me, here's a solution amalgamated from this and other answers on SO.
set #orig_lat=37.46;
set #orig_long=-122.25;
set #bounding_distance=1;
SELECT
*
,((ACOS(SIN(#orig_lat * PI() / 180) * SIN(`lat` * PI() / 180) + COS(#orig_lat * PI() / 180) * COS(`lat` * PI() / 180) * COS((#orig_long - `long`) * PI() / 180)) * 180 / PI()) * 60 * 1.1515) AS `distance`
FROM `cities`
WHERE
(
`lat` BETWEEN (#orig_lat - #bounding_distance) AND (#orig_lat + #bounding_distance)
AND `long` BETWEEN (#orig_long - #bounding_distance) AND (#orig_long + #bounding_distance)
)
ORDER BY `distance` ASC
limit 25;
Easy one ;)
SELECT * FROM `WAYPOINTS` W ORDER BY
ABS(ABS(W.`LATITUDE`-53.63) +
ABS(W.`LONGITUDE`-9.9)) ASC LIMIT 30;
Just replace the coordinates with your required ones. The values have to be stored as double. This ist a working MySQL 5.x example.
Cheers
Try this, it show the nearest points to provided coordinates (within 50 km). It works perfectly:
SELECT m.name,
m.lat, m.lon,
p.distance_unit
* DEGREES(ACOS(COS(RADIANS(p.latpoint))
* COS(RADIANS(m.lat))
* COS(RADIANS(p.longpoint) - RADIANS(m.lon))
+ SIN(RADIANS(p.latpoint))
* SIN(RADIANS(m.lat)))) AS distance_in_km
FROM <table_name> AS m
JOIN (
SELECT <userLat> AS latpoint, <userLon> AS longpoint,
50.0 AS radius, 111.045 AS distance_unit
) AS p ON 1=1
WHERE m.lat
BETWEEN p.latpoint - (p.radius / p.distance_unit)
AND p.latpoint + (p.radius / p.distance_unit)
AND m.lon BETWEEN p.longpoint - (p.radius / (p.distance_unit * COS(RADIANS(p.latpoint))))
AND p.longpoint + (p.radius / (p.distance_unit * COS(RADIANS(p.latpoint))))
ORDER BY distance_in_km
Just change <table_name>. <userLat> and <userLon>
You can read more about this solution here: http://www.plumislandmedia.net/mysql/haversine-mysql-nearest-loc/
You're looking for things like the haversine formula. See here as well.
There's other ones but this is the most commonly cited.
If you're looking for something even more robust, you might want to look at your databases GIS capabilities. They're capable of some cool things like telling you whether a point (City) appears within a given polygon (Region, Country, Continent).
Check this code based on the article Geo-Distance-Search-with-MySQL:
Example: find the 10 nearest hotels to my current location in a 10 miles radius:
#Please notice that (lat,lng) values mustn't be negatives to perform all calculations
set #my_lat=34.6087674878572;
set #my_lng=58.3783670308302;
set #dist=10; #10 miles radius
SELECT dest.id, dest.lat, dest.lng, 3956 * 2 * ASIN(SQRT(POWER(SIN((#my_lat -abs(dest.lat)) * pi()/180 / 2),2) + COS(#my_lat * pi()/180 ) * COS(abs(dest.lat) * pi()/180) * POWER(SIN((#my_lng - abs(dest.lng)) * pi()/180 / 2), 2))
) as distance
FROM hotel as dest
having distance < #dist
ORDER BY distance limit 10;
#Also notice that distance are expressed in terms of radius.
Find nearest Users to my:
Distance in meters
Based in Vincenty's formula
i have User table:
+----+-----------------------+---------+--------------+---------------+
| id | email | name | location_lat | location_long |
+----+-----------------------+---------+--------------+---------------+
| 13 | xxxxxx#xxxxxxxxxx.com | Isaac | 17.2675625 | -97.6802361 |
| 14 | xxxx#xxxxxxx.com.mx | Monse | 19.392702 | -99.172596 |
+----+-----------------------+---------+--------------+---------------+
sql:
-- my location: lat 19.391124 -99.165660
SELECT
(ATAN(
SQRT(
POW(COS(RADIANS(users.location_lat)) * SIN(RADIANS(users.location_long) - RADIANS(-99.165660)), 2) +
POW(COS(RADIANS(19.391124)) * SIN(RADIANS(users.location_lat)) -
SIN(RADIANS(19.391124)) * cos(RADIANS(users.location_lat)) * cos(RADIANS(users.location_long) - RADIANS(-99.165660)), 2)
)
,
SIN(RADIANS(19.391124)) *
SIN(RADIANS(users.location_lat)) +
COS(RADIANS(19.391124)) *
COS(RADIANS(users.location_lat)) *
COS(RADIANS(users.location_long) - RADIANS(-99.165660))
) * 6371000) as distance,
users.id
FROM users
ORDER BY distance ASC
radius of the earth : 6371000 ( in meters)
simpledb.execSQL("CREATE TABLE IF NOT EXISTS " + tablename + "(id INTEGER PRIMARY KEY AUTOINCREMENT,lat double,lng double,address varchar)");
simpledb.execSQL("insert into '" + tablename + "'(lat,lng,address)values('22.2891001','70.780154','craftbox');");
simpledb.execSQL("insert into '" + tablename + "'(lat,lng,address)values('22.2901396','70.7782428','kotecha');");//22.2904718 //70.7783906
simpledb.execSQL("insert into '" + tablename + "'(lat,lng,address)values('22.2863155','70.772108','kkv Hall');");
simpledb.execSQL("insert into '" + tablename + "'(lat,lng,address)values('22.275993','70.778076','nana mava');");
simpledb.execSQL("insert into '" + tablename + "'(lat,lng,address)values('22.2667148','70.7609386','Govani boys hostal');");
double curentlat=22.2667258; //22.2677258
double curentlong=70.76096826;//70.76096826
double curentlat1=curentlat+0.0010000;
double curentlat2=curentlat-0.0010000;
double curentlong1=curentlong+0.0010000;
double curentlong2=curentlong-0.0010000;
try{
Cursor c=simpledb.rawQuery("select * from '"+tablename+"' where (lat BETWEEN '"+curentlat2+"' and '"+curentlat1+"') or (lng BETWEEN '"+curentlong2+"' and '"+curentlong1+"')",null);
Log.d("SQL ", c.toString());
if(c.getCount()>0)
{
while (c.moveToNext())
{
double d=c.getDouble(1);
double d1=c.getDouble(2);
}
}
}
catch (Exception e)
{
e.printStackTrace();
}
It sounds like you want to do a nearest neighbour search with some bound on the distance. SQL does not support anything like this as far as I am aware and you would need to use an alternative data structure such as an R-tree or kd-tree.
MS SQL Edition here:
DECLARE #SLAT AS FLOAT
DECLARE #SLON AS FLOAT
SET #SLAT = 38.150785
SET #SLON = 27.360249
SELECT TOP 10 [LATITUDE], [LONGITUDE], SQRT(
POWER(69.1 * ([LATITUDE] - #SLAT), 2) +
POWER(69.1 * (#SLON - [LONGITUDE]) * COS([LATITUDE] / 57.3), 2)) AS distance
FROM [TABLE] ORDER BY 3
Sounds like you should just use PostGIS, SpatialLite, SQLServer2008, or Oracle Spatial. They can all answer this question for you with spatial SQL.
+----+-----------------------+---------+--------------+---------------+
| id | email | name | location_lat | location_long |
+----+-----------------------+---------+--------------+---------------+
| 7 | test#gmail.com | rembo | 23.0249256 | 72.5269697 |
| 25 | test1#gmail.com. | Rajnis | 23.0233221 | 72.5342112 |
+----+-----------------------+---------+--------------+---------------+
$lat = 23.02350629;
$long = 72.53230239;
DB::
SELECT
("
SELECT
*
FROM
(
SELECT
,
(
( ( acos( sin(( ". $ lat ." * pi() / 180)) * sin(( lat * pi() / 180)) + cos(( ". $ lat ." pi() / 180 )) * cos(( lat * pi() / 180)) * cos((( ". $ long ." - LONG) * pi() / 180))) ) * 180 / pi() ) * 60 * 1.1515 * 1.609344
)
as distance
FROM
users
)
users
WHERE
distance <= 2");
In extreme cases this approach fails, but for performance, I've skipped the trigonometry and simply calculated the diagonal squared.
Mysql query for search coordinates with distance limit and where condition
SELECT id, ( 3959 * acos( cos( radians('28.5850154') ) * cos( radians(latitude) ) * cos( radians( longitude ) - radians('77.07207489999999') ) + sin( radians('28.5850154') ) * sin( radians( latitude ) ) ) ) AS distance FROM `vendors` HAVING distance < 5;
This problem is not very hard at all, but it gets more complicated if you need to optimize it.
What I mean is, do you have 100 locations in your database or 100 million? It makes a big difference.
If the number of locations is small, get them out of SQL and into code by just doing ->
Select * from Location
Once you get them into code, calculate the distance between each lat/lon and your original with the Haversine formula and sort it.
SELECT postcode, lat, lng,
truncate(
(degrees(acos
(sin(radians(lat))
*
sin( radians('.$latitude.'))
+
cos(radians(lat))
*
cos( radians('.$latitude.'))
*
cos( radians(lng - ('.$longitude.')))
)
)
* 69.172), 2)
as distance
FROM myData
This query calculates distance (in miles). But when I check distance for same lat and longitude at google maps my result doesnt match. If the distance is around 10 miles then my result is a bit accurate, but over that it gets wrong (for example, my result showed 13 miles and google showed 22 miles for same post code values)
I got this query from http://forums.mysql.com/read.php?23,3868,3868#msg-3868
How can I get it accurate. Any ideas?
Thanks for help.
UPDATE
I tried #Blixt code in PHP. Picked up 2 sample postcodes and their lats longs
//B28 9ET
$lat1 = 52.418819;
$long1 = -1.8481053;
//CV5 8BX
$lat2 = 52.4125573;
$long2 = -1.5407743;
$dtr = M_PI / 180;
$latA = $lat1 * $dtr;
$lonA = $long1 * $dtr;
$latB = $lat2 * $dtr;
$lonB = $long2 * $dtr;
$EarthRadius = 3958.76; //miles
echo $distance = $EarthRadius * acos(cos($latA) * cos($latB) * cos($lonB - $lonA) + sin($latA) * sin($latB));
Results:
My app - 12.95 miles
Google - 17.8 miles
Any ideas how to get it right?
Have a look at this source code. When I tested it against various other measurement services it seemed to get the same results. It's C# but the math should be easy enough to convert.
Here are the relevant pieces:
public const double EarthRadius = 6371.0072; // Kilometers
//public const double EarthRadius = 3958.76; // Miles
/* ... */
const double dtr = Math.PI / 180;
double latA = this.Latitude * dtr;
double lonA = this.Longitude * dtr;
double latB = other.Latitude * dtr;
double lonB = other.Longitude * dtr;
return GpsLocation.EarthRadius * Math.Acos(Math.Cos(latA) * Math.Cos(latB) * Math.Cos(lonB - lonA) + Math.Sin(latA) * Math.Sin(latB));
Note: The Earth is not perfectly spherical, so the constants used may differ. There is no easy way to make the measurements truly exact. See Wikipedia.