[R] kernel smoothing of disease rates at locations

[Roger D. Peng]

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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