anchor.diff:  "nhd_12979511","swimms","maxdepth",11.2776
   "nhd_13124174","swimms","maxdepth",4.2672
   "nhd_1797591","swimms","maxdepth",3.9624
  -NA,"swimms","maxdepth",NA
   "nhd_13346902","swimms","maxdepth",14.3256
   "nhd_6817260","swimms","maxdepth",1.8288
  -NA,"swimms","maxdepth",2.4384
   "nhd_120052474","swimms","maxdepth",3.6576
   "nhd_6808490","swimms","maxdepth",6.096
   "nhd_13394417","swimms","maxdepth",21.6408
   "nhd_2264893","swimms","maxdepth",7.62
   "nhd_13396007","swimms","maxdepth",7.0104
   "nhd_2266141","swimms","maxdepth",9.4488
  -NA,"swimms","maxdepth",NA
  -NA,"swimms","maxdepth",NA
   "nhd_2264157","swimms","maxdepth",5.1816
   "nhd_13409634","swimms","maxdepth",4.2672
  -NA,"swimms","maxdepth",2.1336
  -"nhd_14704056","swimms","maxdepth",NA
   "nhd_6842791","swimms","maxdepth",6.096
   "nhd_2643852","swimms","maxdepth",3.048
  -NA,"swimms","maxdepth",4.572
  -NA,"swimms","maxdepth",NA
  -NA,"swimms","maxdepth",NA
   "nhd_13409672","swimms","maxdepth",2.4384
   "nhd_6807830","swimms","maxdepth",4.572
   "nhd_13344010","swimms","maxdepth",7.0104
  -NA,"swimms","maxdepth",1.524
   "nhd_13117630","swimms","maxdepth",4.8768
  -NA,"swimms","maxdepth",5.1816
  -NA,"swimms","maxdepth",0.9144
   "nhd_13394189","swimms","maxdepth",11.5824
  
positive.code: "nhd_6817066","swimms","maxdepth",1.2192
  "nhd_1816231","swimms","maxdepth",16.764
  "nhd_13394777","swimms","maxdepth",3.048
  NA,"swimms","maxdepth",5.1816
  "nhd_14729154","swimms","maxdepth",2.7432
  NA,"swimms","maxdepth",2.4384
  "nhd_1849957","swimms","maxdepth",3.3528
  "nhd_2268385","swimms","maxdepth",2.7432
  NA,"swimms","maxdepth",1.524
  "nhd_2646850","swimms","maxdepth",0.9144
  "nhd_2643864","swimms","maxdepth",1.524
  "nhd_9029719","swimms","maxdepth",1.2192
  "nhd_9026301","swimms","maxdepth",1.8288
  "nhd_13343494","swimms","maxdepth",4.572
  "nhd_2644332","swimms","maxdepth",3.048
  NA,"swimms","maxdepth",0.9144
  "nhd_13296408","swimms","maxdepth",2.4384
  "nhd_13345458","swimms","maxdepth",6.4008
  "nhd_167120824","swimms","maxdepth",5.7912
  "nhd_13294782","swimms","maxdepth",3.048
  "nhd_14701618","swimms","maxdepth",4.2672
  "nhd_13394251","swimms","maxdepth",0.9144
  "nhd_13393599","swimms","maxdepth",2.1336
  NA,"swimms","maxdepth",5.4864
  "nhd_2643470","swimms","maxdepth",NA
  "nhd_2643756","swimms","maxdepth",3.9624
  "nhd_2643800","swimms","maxdepth",NA
  "nhd_2647170","swimms","maxdepth",1.8288
  "nhd_13395257","swimms","maxdepth",7.9248
  "nhd_9035775","swimms","maxdepth",7.0104
  "nhd_6807812","swimms","maxdepth",3.048
  "nhd_1797531","swimms","maxdepth",9.7536
  "nhd_2262519","swimms","maxdepth",0.9144
  NA,"swimms","maxdepth",2.1336
  NA,"swimms","maxdepth",NA
  "nhd_13131955","swimms","maxdepth",15.24
  NA,"swimms","maxdepth",1.2192
  "nhd_12991241","swimms","maxdepth",1.524
  "nhd_13124214","swimms","maxdepth",7.0104
  NA,"swimms","maxdepth",14.0208
  "nhd_6817206","swimms","maxdepth",6.096
  "nhd_14445888","swimms","maxdepth",11.5824
  "nhd_9032837","swimms","maxdepth",8.2296
  "nhd_13121052","swimms","maxdepth",2.7432
  "nhd_2264797","swimms","maxdepth",8.2296
  "nhd_13078251","swimms","maxdepth",6.7056
  NA,"swimms","maxdepth",2.4384
  "nhd_12980471","swimms","maxdepth",13.4112
  NA,"swimms","maxdepth",NA
  NA,"swimms","maxdepth",4.572
  NA,"swimms","maxdepth",6.7056
  "nhd_14783605","swimms","maxdepth",3.048
  NA,"swimms","maxdepth",6.096
  "nhd_13393489","swimms","maxdepth",14.6304
  "nhd_6792249","swimms","maxdepth",11.2776
  "nhd_14726112","swimms","maxdepth",10.0584
  "nhd_6842381","swimms","maxdepth",0.9144
  NA,"swimms","maxdepth",2.7432
  "nhd_9026373","swimms","maxdepth",9.4488
  NA,"swimms","maxdepth",2.1336
  "nhd_2262735","swimms","maxdepth",4.2672
  "nhd_2260893","swimms","maxdepth",10.9728
  NA,"swimms","maxdepth",9.144
  "nhd_14443274","swimms","maxdepth",6.096
  NA,"swimms","maxdepth",6.096
  "nhd_13135397","swimms","maxdepth",NA
  NA,"swimms","maxdepth",2.4384
  "nhd_13096412","swimms","maxdepth",3.048
  "nhd_13105903","swimms","maxdepth",3.048
  NA,"swimms","maxdepth",4.572
  "nhd_2260857","swimms","maxdepth",4.572
  NA,"swimms","maxdepth",NA
  "nhd_13343156","swimms","maxdepth",5.4864
  "nhd_1849755","swimms","maxdepth",7.62
  "nhd_13282702","swimms","maxdepth",18.288
  "nhd_120052743","swimms","maxdepth",10.0584
  "nhd_13103947","swimms","maxdepth",14.3256
  "nhd_13078547","swimms","maxdepth",6.096
  NA,"swimms","maxdepth",2.4384
  "nhd_13103827","swimms","maxdepth",1.8288
  NA,"swimms","maxdepth",8.2296
  "nhd_14767942","swimms","maxdepth",7.62
  NA,"swimms","maxdepth",1.2192
  "nhd_12176150","swimms","maxdepth",1.8288
  NA,"swimms","maxdepth",4.8768
  "nhd_13394725","swimms","maxdepth",3.3528
  NA,"swimms","maxdepth",5.1816
  NA,"swimms","maxdepth",2.1336
  "nhd_13395325","swimms","maxdepth",2.1336
  NA,"swimms","maxdepth",3.6576
  "nhd_12982255","swimms","maxdepth",2.4384
  "nhd_1797573","swimms","maxdepth",2.1336
  "nhd_1816493","swimms","maxdepth",9.144
  NA,"swimms","maxdepth",5.7912
  "nhd_2643996","swimms","maxdepth",3.6576
  NA,"swimms","maxdepth",4.8768
  "nhd_13078155","swimms","maxdepth",5.7912
  "nhd_6842549","swimms","maxdepth",1.2192
  "nhd_14726566","swimms","maxdepth",9.144
  NA,"swimms","maxdepth",2.1336
  "nhd_2266615","swimms","maxdepth",1.524
  NA,"swimms","maxdepth",3.3528
  "nhd_9030089","swimms","maxdepth",5.7912
  "nhd_6866407","swimms","maxdepth",1.524
  "nhd_9026391","swimms","maxdepth",3.6576
  NA,"swimms","maxdepth",8.2296
  "nhd_6819524","swimms","maxdepth",1.2192
  "nhd_9035717","swimms","maxdepth",13.4112
  "nhd_13294424","swimms","maxdepth",2.1336
  "nhd_1855223","swimms","maxdepth",9.144
  "nhd_6819422","swimms","maxdepth",6.7056
  NA,"swimms","maxdepth",0.9144
  NA,"swimms","maxdepth",5.1816
  "nhd_13399227","swimms","maxdepth",4.572
  "nhd_1849537","swimms","maxdepth",11.8872
  "nhd_13343366","swimms","maxdepth",15.24
  "nhd_6808414","swimms","maxdepth",7.3152
  "nhd_13285316","swimms","maxdepth",3.048
  "nhd_120052171","swimms","maxdepth",9.144
  NA,"swimms","maxdepth",4.2672
  "nhd_9032663","swimms","maxdepth",2.1336
  "nhd_12988109","swimms","maxdepth",7.3152
  "nhd_13393503","swimms","maxdepth",4.2672
  "nhd_14704036","swimms","maxdepth",1.524
  "nhd_6842707","swimms","maxdepth",3.048
  "nhd_6819954","swimms","maxdepth",8.8392
  NA,"swimms","maxdepth",NA
  "nhd_13394425","swimms","maxdepth",9.144
  NA,"swimms","maxdepth",0.9144
  "nhd_12174532","swimms","maxdepth",15.24
  NA,"swimms","maxdepth",4.8768
  "nhd_13395149","swimms","maxdepth",7.0104
  "nhd_12991001","swimms","maxdepth",7.3152
  "nhd_9035945","swimms","maxdepth",20.4216
  "nhd_13343428","swimms","maxdepth",7.62
  "nhd_2646732","swimms","maxdepth",1.8288
  NA,"swimms","maxdepth",0.9144
  "nhd_9029899","swimms","maxdepth",11.8872
  "nhd_13393943","swimms","maxdepth",4.572
  "nhd_2264725","swimms","maxdepth",8.2296
  
negative.code: "nhd_14726454","swimms","maxdepth",6.096
  "nhd_6808758","swimms","maxdepth",5.7912
  "nhd_13395391","swimms","maxdepth",13.4112
  "nhd_6819622","swimms","maxdepth",3.3528
  "nhd_13135195","swimms","maxdepth",2.1336
  "nhd_13393787","swimms","maxdepth",14.0208
  "nhd_2260997","swimms","maxdepth",8.5344
  "nhd_13395311","swimms","maxdepth",2.7432
  "nhd_1850283","swimms","maxdepth",2.1336
  "nhd_13104001","swimms","maxdepth",4.8768
  