It is certainly possible to get negative values when smoothing, especially on
the edges. But we cannot reproduce your problem because you did not provide any
code.
-roger
Oarabile Molaodi wrote:> I want to do kernel smoothing on the standardised mortality rates at
> specified location(x-y coordinates) and be able to produce contour map.
> I've tried to use the package called fields in R (function smooth.2d)
> but the problem is I get negative results after smoothing and I do not
> understand why? Your contributions will be highly appreciated or if
> there is any package that can do this I will be happy to know about it.
> Thanks in advance for your comments.
> Oarabile
>
> Below is how my data in R looks like
> Xcoord Ycoord smr
> 1 383894.70 653202.8 1.5816327
> 2 339053.00 631770.9 1.0003473
> 3 369164.50 609973.2 1.2943872
> 4 313477.70 640382.8 0.9443508
> 5 290748.80 695088.8 1.1662125
> 6 287547.50 679829.6 0.9433962
> 7 259031.90 704478.3 1.0184905
> 8 329107.60 585753.3 1.0445860
> 9 292170.20 578978.2 1.1287758
> 10 268330.90 564281.7 0.9805996
> 11 227395.50 561524.6 1.1947431
> 12 310130.70 689395.0 1.0991957
> 13 325756.00 696565.6 1.1734694
> 14 339427.20 713217.2 0.8724100
> 15 391752.10 805661.5 1.2483221
> 16 385935.90 851044.5 1.0558140
> 17 372471.20 826373.7 1.4220183
> 18 354901.70 791107.2 0.9175084
> 19 324944.10 842040.8 1.0447080
> 20 275672.50 802570.4 0.9899329
> 21 320750.00 954769.7 1.0866834
> 22 243489.20 832748.8 1.0995658
> 23 166559.70 786365.3 1.0401267
> 24 288160.80 846054.4 1.0299003
> 25 220347.00 869181.0 0.9529435
> 26 175863.63 822593.9 0.9902252
> 27 246114.40 938419.3 0.8909370
> 28 359070.60 669738.3 0.9883721
> 29 320614.70 670434.2 1.1288534
> 30 331414.80 659972.3 0.9070866
> 31 299336.90 666122.9 0.7969349
> 32 156965.25 708047.7 1.1410460
> 33 253867.30 674916.5 0.9256710
> 34 249188.40 674272.8 1.0869565
> 35 272463.00 679495.3 0.8576698
> 36 252643.80 611378.4 0.8615611
> 37 212637.35 643725.0 0.8596604
> 38 234751.95 691803.4 0.9706546
> 39 264856.20 644684.8 0.8468395
> 40 253949.30 653042.5 0.8106169
> 41 260412.35 663552.2 0.9253686
> 42 270807.60 657454.0 0.9002826
> 43 228477.30 670443.2 1.0782502
> 44 248215.30 641897.3 0.9240407
> 45 229797.50 596059.0 1.1579197
> 46 291725.00 635771.8 0.8908766
> 47 278012.80 667982.0 1.0240000
> 48 279490.80 659761.6 0.9828301
> 49 242791.70 662651.8 1.0230584
> 50 263217.20 675295.2 0.9759817
> 51 341138.80 754471.3 0.9505541
> 52 334963.00 735075.4 0.9264498
> 53 286139.70 733611.6 0.9052453
> 54 354015.60 1025696.8 0.8905506
> 55 455775.60 1201636.0 1.0862620
> 56 88429.32 854994.4 0.9577015
>
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