Download elevation data for the state of California from the USGS's NED system

download_ned.py

"""
Download elevation data for California from with USGS's NED data
"""
import os
import urllib

CALIFORNIA_TILES = {
    '42120': 'n42w120_13',
    '42121': 'n42w121_13',
    '42122': 'n42w122_13',
    '42123': 'n42w123_13',
    '42124': 'n42w124_13',
    '42125': 'n42w125_13',
    '37116': 'n37w116_13',
    '37117': 'n37w117_13',
    '37118': 'n37w118_13',
    '37119': 'n37w119_13',
    '37120': 'n37w120_13',
    '34115': 'n34w115_13',
    '34116': 'n34w116_13',
    '34117': 'n34w117_13',
    '34118': 'n34w118_13',
    '34119': 'n34w119_13',
    '34120': 'n34w120_13',
    '34121': 'n34w121_13',
    '40120': 'n40w120_13',
    '40121': 'n40w121_13',
    '40122': 'n40w122_13',
    '40123': 'n40w123_13',
    '40124': 'n40w124_13',
    '40125': 'n40w125_13',
    '37121': 'n37w121_13',
    '39123': 'n39w123_13',
    '36115': 'n36w115_13',
    '36116': 'n36w116_13',
    '36117': 'n36w117_13',
    '36118': 'n36w118_13',
    '36119': 'n36w119_13',
    '36120': 'n36w120_13',
    '36121': 'n36w121_13',
    '36122': 'n36w122_13',
    '33115': 'n33w115_13',
    '33116': 'n33w116_13',
    '33117': 'n33w117_13',
    '33118': 'n33w118_13',
    '33119': 'n33w119_13',
    '39119': 'n39w119_13',
    '39120': 'n39w120_13',
    '39121': 'n39w121_13',
    '39122': 'n39w122_13',
    '41120': 'n41w120_13',
    '41121': 'n41w121_13',
    '41122': 'n41w122_13',
    '41123': 'n41w123_13',
    '41124': 'n41w124_13',
    '41125': 'n41w125_13',
    '43120': 'n43w120_13',
    '43121': 'n43w121_13',
    '43122': 'n43w122_13',
    '43123': 'n43w123_13',
    '43124': 'n43w124_13',
    '43125': 'n43w125_13',
    '35115': 'n35w115_13',
    '35116': 'n35w116_13',
    '35117': 'n35w117_13',
    '35118': 'n35w118_13',
    '35119': 'n35w119_13',
    '35120': 'n35w120_13',
    '35121': 'n35w121_13',
    '39124': 'n39w124_13',
    '37122': 'n37w122_13',
    '37123': 'n37w123_13',
    '38118': 'n38w118_13',
    '38119': 'n38w119_13',
    '38120': 'n38w120_13',
    '38121': 'n38w121_13',
    '38122': 'n38w122_13',
    '38123': 'n38w123_13',
    '38124': 'n38w124_13',
}

BASE_URL = 'http://gisdata.usgs.gov/TDDS/DownloadFile.php?TYPE=ned3g_zip&ORIG=TNM&FNAME=%(name)s.zip'
DOWNLOAD_PATH = '<your_download_path>'


def download_tile(number, name):
    """
    Download a zipped up version of an ArcGRID raster tile from USGS
    """
    url = BASE_URL % dict(number=number, name=name.replace("_13", ""))
    save_as = os.path.join(DOWNLOAD_PATH, '%s_%s.zip' % (number, name))
    if os.path.exists(save_as):
        print "Skipping %s because we've already got it" % save_as
        return False
    else:
        print "Retrieving %s" % url
        urllib.urlretrieve(url, save_as)
        return True



if __name__ == '__main__':
    for number, name in CALIFORNIA_TILES.items():
        download_tile(number, name)