# Esri ARC/INFO ASCII GRID reader
Designed to handle large files. Tested with SRTM 90m Digital Elevation Data: http://srtm.csi.cgiar.org/.
## Usage
### Single tile handling
```php
<?php
use infojunkie\EsriGrid;
$max = -99999;
$min = 100000;
$file = new GridFile('test_dem1.txt');
$grid = $file->getGridFromPoints(0, 0, 140, 230, 'calc_stats');
echo "max: $max, min: $min\n";
var_dump($grid);
function calc_stats($x, $y, $elevation) {
global $max, $min;
echo "$x, $y: $elevation\n";
if (!is_null($elevation)) {
$max = max($max, $elevation);
$min = min($min, $elevation);
}
}
?>
```
### Multiple tile handling
```php
<?php
use infojunkie\EsriGrid;
$files = new GridFiles(array(
'test_dem1.txt',
'test_dem2.txt',
'test_dem3.txt',
'test_dem4.txt',
'test_dem5.txt',
'test_dem6.txt',
));
$grid = $files->getGridFromPoints(175, 225, 325, 675, 'calc_stats');
echo "max: $max, min: $min\n";
var_dump($grid);
?>
```
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