[R-sig-Geo] How do I read and plot .nc data in R?

[Eko Susilo]

Could somebody help me to figure out my data

I have .nc data around Indonesia water (attached below)

I use R to open and plot it. This is my syntax

nc <- open.ncdf(choose.files('D:/R/yfin_pelikan/yfin_input', caption = 
'Select netcdf Files .....'))
print (nc)

# Read the variable

adl <- nc$var[[1]]
varsize <- adl$varsize
ndims <- adl$ndims
nt <- varsize[ndims]

start <- rep(1,ndims) # begin with start=(1,1,1,...,1)
start[ndims] <- j # change to start=(1,1,1,...,i) to read timestep i
count <- varsize # begin w/count=(nx,ny,nz,...,nt), reads entire var
count[ndims] <- 1 # change to count=(nx,ny,nz,...,1) to read 1 tstep

data <- get.var.ncdf(nc, adl, start=start, count=count )

# plot the map

jet.colors <- colorRampPalette(c('#00007F', 'blue', '#007FFF', 
'cyan','#7FFF7F', 'yellow', '#FF7F00', 'red', '#7F0000'))

plot.adl <- levelplot(data,
col.regions = jet.colors(255), at=seq(0, 1, 0.005),
yscale.components=yscale.raster.subticks,
xscale.components=xscale.raster.subticks,
margin=FALSE, ylab='latitude', xlab='longitude', main='test')
print(plot.adl + layer(sp.lines(indo.map, lwd=1, col='black')))

# The results is good bad not georreference so i can't overlay with the 
base map (costaline)...

# So i try to convert it to raster

# Convert it to raster and re-plot

y <- raster(data.adl, xmn=-20, xmx=25, ymn=90, ymx=144)
projection(y) <- CRS("+proj=longlat +datum=WGS84")

plot.y <- levelplot(y,
col.regions = jet.colors(255), at=seq(0, 1, 0.005),
yscale.components=yscale.raster.subticks,
xscale.components=xscale.raster.subticks,
margin=FALSE, ylab='latitude', xlab='longitude', main='test')
print(plot.y + layer(sp.lines(indo.map, lwd=1, col='black')))

# The result is not good..

Attached file:

data (https://onedrive.live.com/redir?resid=6FFDD661570C7D0A%21165 
<https://www.researchgate.net/go.Deref.html?url=https%3A%2F%2Fonedrive.live.com%2Fredir%3Fresid%3D6FFDD661570C7D0A%2521165>)

result1 (https://onedrive.live.com/redir?resid=6FFDD661570C7D0A%21164 
<https://www.researchgate.net/go.Deref.html?url=https%3A%2F%2Fonedrive.live.com%2Fredir%3Fresid%3D6FFDD661570C7D0A%2521164>)

result2 (https://onedrive.live.com/redir?resid=6FFDD661570C7D0A%21163 
<https://www.researchgate.net/go.Deref.html?url=https%3A%2F%2Fonedrive.live.com%2Fredir%3Fresid%3D6FFDD661570C7D0A%2521163>)


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