[R] Please help me to produce smoothed contour plots

[Simon Wood]

One approach would be to smooth the data using `gam' from package `mgcv'. 
`vis.gam' will contour the resulting smoothed fit if you select 
`plot.type="contour"'. If the results look ok but you want finer control of 
what the plot looks like then `predict.gam' can be used to predict from the 
fitted smooth on any regular grid suitable for supplying to `contour' 
(although you have to supply the grid!).

On Wednesday 01 October 2008 13:05, Mark wrote:
> Please help me to produce smoothed contour plots.
>
> I have dependent data generated at regular intervals of two independent
> variables and would like to produce smoothed contour plots - I cannot get
> interp (alima) to produce cubic interpolations of the data, only linear
> ones. I'm interested in smoothing as the data generation process is
> stochastic and produces small variations which I'd rather 'smooth' away. I
> cannot spot what is different about my data from the examples in (akima)
> which prevents this working.
>
> here is an example of my data:
> > x
>
>    0  50 100 150 200 250 300 350 400 450 500   0  50 100 150 200 250 300
> 350 400
>  [21] 450 500   0  50 100 150 200 250 300 350 400 450 500   0  50 100 150
> 200 250 300
>  [41] 350 400 450 500   0  50 100 150 200 250 300 350 400 450 500   0  50
> 100 150 200
>  [61] 250 300 350 400 450 500   0  50 100 150 200 250 300 350 400 450 500
> 0  50 100
>  [81] 150 200 250 300 350 400 450 500   0  50 100 150 200 250 300 350 400
> 450 500   0
> [101]  50 100 150 200 250 300 350 400 450 500   0  50 100 150 200 250 300
> 350 400 450
> [121] 500
>
> > y
>
>   [1] 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.05 0.05 0.05
> 0.05 0.05
>  [17] 0.05 0.05 0.05 0.05 0.05 0.05 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10
> 0.10 0.10
>  [33] 0.10 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.20 0.20
> 0.20 0.20
>  [49] 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.25 0.25 0.25 0.25 0.25 0.25 0.25
> 0.25 0.25
>  [65] 0.25 0.25 0.30 0.30 0.30 0.30 0.30 0.30 0.30 0.30 0.30 0.30 0.30 0.35
> 0.35 0.35
>  [81] 0.35 0.35 0.35 0.35 0.35 0.35 0.35 0.35 0.40 0.40 0.40 0.40 0.40 0.40
> 0.40 0.40
>  [97] 0.40 0.40 0.40 0.45 0.45 0.45 0.45 0.45 0.45 0.45 0.45 0.45 0.45 0.45
> 0.50 0.50
> [113] 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50 0.50
>
> > zz
>
>   [1] 105136  98444  95021  79375  72532  64392  57819  44413  40610  26083
> 18077
>  [12]  96188  87863  80205  69503  61000  50387  44306  33432  22958  17575
> 10892
>  [23]  88402  75263  65109  63717  50998  39837  28576  25960  17531
> 8510   5733
>  [34]  70806  59245  53970  46113  38455  30492  23836  17870  10954
> 5218   2266
>  [45]  68272  58610  47854  34834  32363  24238  19236  11789   6206
> 2515   2141
>  [56]  58448  47706  43001  39592  22840  18264  11564   6292   2915
> 2228   2090
>  [67]  55817  47680  38460  31693  21331  13161   8050   3162   2302
> 2120   1990
>  [78]  54078  43720  32828  22618  17039   8524   4846   2392   2154
> 2068   2008
>  [89]  47459  39734  29525  21325  10602   6406   3525   2207   2062
> 2014   1952
> [100]  47630  34965  28452  18966   8386   5726   2351   2145   2052
> 1999   1960
> [111]  42173  34339  27449  16743   9643   2866   2208   2096   2018
> 1937   1886
>
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>
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>
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-- 
> Simon Wood, Mathematical Sciences, University of Bath, Bath, BA2 7AY UK
> +44 1225 386603  www.maths.bath.ac.uk/~sw283