Greetings to all,
I have monthly mean satellite image time series that come in a 4-column
text file each. I have dozens of such files. Every line correspond to a
pixel that is projected onto a regular ISIN grid. The first column is
the ISIN grid number (same coordinates for a given grid number in every
file), the second column is the latitude, the third column is the
longitude and the last column is the value of the satellite measurement.
Every file contain a varying number of lines (no NAs), although the lat
and lon associated for a given ISIN grid number is the same in every file.
I read the examples related with the STFDF class and understood it.
However this is not a good solution for me as I have a lot of holes in
my data. I would therefore like to place these time series into an
irregular STSDF spacetime format. I could not find any information on
how to achieve that. I would appreciate it very much if you could help
me construct the irregular STSDF (or STIDF?) object. How to instruct the
STSDF function so that it understands what goes where?
Below is a sample code that involves 3 image files, each containing
different pixels. I do not have handy a complete list of a list of all
grid numbers for which there is at least one pixel. But I could easily
generate it by reading in every image in a same data frame and producing
a list of the unique values of the first column. For now I construct a
SpatialPoints object but eventually I will be working with SpatialPixels.
thanks a lot for your kindly help.
Best
Servet
library(sp)
library(spacetime)
img200206 <- data.frame(rbind(
c(10849178, -4.979167, -19.99302, 1.1542897E-03),
c(10849179, -4.979167, -19.95120, 1.3418309E-03),
c(10849180, -4.979167, -19.90937, 1.3988283E-03)))
img200207 <- data.frame(rbind(
c(10849178, -4.979167, -19.99302, 1.2843144E-03),
c(10849179, -4.979167, -19.95120, 1.1260216E-03)))
img200208 <- data.frame(rbind(
c(10849179, -4.979167, -19.95120, 1.5001300E-03),
c(10849180, -4.979167, -19.90937, 1.4793734E-03)))
coordinates(img200206)=c("X3","X2")
coordinates(img200207)=c("X3","X2")
coordinates(img200208)=c("X3","X2")
time = xts(1:3, as.POSIXct(c("2002-06-01","2002-07-01","2002-08-01")))
#This is where I am stuck at
mySTSDF = STSDF( ... )
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