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May 3, 2019 13:28
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Create raster from SAFRAN csv file
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# safran 2 raster | |
library(data.table) | |
library(raster) | |
library(sf) | |
# ##### FONCTIONS ##### | |
# genere 1 raster à partir de DT(data.table) pour la variable et la date spécifiées | |
DT2rast <- function(extr_date, DT, varname) { | |
varlist <- c("LAMBX", "LAMBY", varname) | |
DTi <- DT[DATE==extr_date, ..varlist] | |
dfi <- as.data.frame(DTi) | |
dfi$LAMBX <- dfi$LAMBX * 100 | |
dfi$LAMBY <- dfi$LAMBY * 100 | |
rasterFromXYZ(as.data.frame(dfi), crs=CRS("+init=EPSG:27572"), digits=0) | |
} | |
# genere 1 stack raster à partir de DT(data.table) | |
# pour la variable, la plage temporelle et l'étendue spécifiées | |
safran2rast <- function(DT, varname, d_date, f_date, etendue_l2e=NULL) { | |
varlist <- c("LAMBX", "LAMBY", "DATE", varname) | |
seq_dates <- strftime(seq(d_date, f_date, by="days"), "%Y%m%d") | |
if (!is.null(etendue_l2e)) { | |
# subset etendue Lambert2 en hm | |
ethm <- round(etendue_l2e/100, 0) | |
DT <- DT[LAMBX>ethm[1] & LAMBX<ethm[3] & LAMBY>ethm[2] & LAMBY<ethm[4]] | |
DT <- DT[DATE %in% seq_dates,..varlist] | |
} else { | |
DT <- DT[DATE %in% seq_dates,..varlist] | |
} | |
list_raster <- lapply(seq_dates, DT2rast, DT, varname) | |
stack(list_raster) | |
} | |
# genere grille points à partie de DT(data.table) pour la date spécifiée | |
DT2sp <- function(extr_date, DT) { | |
DTi <- DT[DATE==extr_date] | |
pts <- as.data.frame(DTi) | |
pts$coordx <- pts$LAMBX * 100 | |
pts$coordy <- pts$LAMBY * 100 | |
geomdef <- paste0("POINT(", pts$coordx, " ", pts$coordy,")") | |
sfc <- st_as_sfc(geomdef, crs=27572) | |
st_geometry(pts) <- sfc | |
pts | |
} | |
# ##### EXEMPLES D'UTILISATION ##### | |
# ---- parametre : fichier en entree ---- | |
setwd("D:/MeteoFrance/Safran-Isba données quotidiennes") | |
f_safran <- "SIM2_2010_2017.csv" | |
DT_safran <- fread(f_safran, header = TRUE) | |
# etendue de l'Occitanie en Lambert 2 etendu ? | |
sf_reg <- st_read("regions-20180101-shp/regions-20180101.shp") | |
sf_occ <- sf_reg[sf_reg$nom=="Occitanie",] | |
sf_occ_l2 <- st_transform(sf_occ, 27572) | |
# etendue format xmin, ymin, xmax, ymax | |
etendue <- st_bbox(sf_occ_l2) | |
# dates debut et fin | |
jour1 <- as.Date("2014-01-01") | |
jourN <- as.Date("2014-12-31") | |
# ---- exemple 1 : process stack (multitemporel, 1 variable, etendue region) ---- | |
stack_tm <- safran2rast(DT_safran, varname="T_Q", d_date=jour1, f_date=jourN, | |
etendue_l2e=etendue) | |
stack_tn <- safran2rast(DT_safran, varname="TINF_H_Q", d_date=jour1, f_date=jourN, | |
etendue_l2e=etendue) | |
stack_tx <- safran2rast(DT_safran, varname="TSUP_H_Q", d_date=jour1, f_date=jourN, | |
etendue_l2e=etendue) | |
stack_rr <- safran2rast(DT_safran, varname="PRELIQ_Q", d_date=jour1, f_date=jourN, | |
etendue_l2e=etendue) | |
writeRaster(stack_tm, "output_safran/tm_occitanie_2014.tif", overwrite=T) | |
writeRaster(stack_tn, "output_safran/tn_occitanie_2014.tif", overwrite=T) | |
writeRaster(stack_tx, "output_safran/tx_occitanie_2014.tif", overwrite=T) | |
writeRaster(stack_rr, "output_safran/rr_occitanie_2014.tif", overwrite=T) | |
# ... extraire temp + prec montpellier | |
cefe_l2e <- matrix(c(723548, 1849625), ncol=2) | |
cefe_stats <- data.frame( | |
dates_ = strftime(seq(jour1, jourN, by="days"), "%Y%m%d"), | |
tm = as.numeric(extract(stack_tm, cefe_l2e)), | |
tn = as.numeric(extract(stack_tn, cefe_l2e)), | |
tx = as.numeric(extract(stack_tx, cefe_l2e)), | |
rr = as.numeric(extract(stack_rr, cefe_l2e)) | |
) | |
write.csv2(cefe_stats, "output/cefe_stats.csv", row.names = F) | |
# ---- exemple 2 : process raster (1 jour, 1 variable, tte la France) ---- | |
raster_tm_0703 <- DT2rast("20140929", DT_safran, "T_Q") | |
raster_tn_0703 <- DT2rast("20140929", DT_safran, "TINF_H_Q") | |
raster_tx_0703 <- DT2rast("20140929", DT_safran, "TSUP_H_Q") | |
raster_rr_0703 <- DT2rast("20140929", DT_safran, "PRELIQ_Q") | |
writeRaster(raster_tm_0703, "output_safran/tm_france_20140929.tif") | |
writeRaster(raster_tn_0703, "output_safran/tn_france_20140929.tif") | |
writeRaster(raster_tx_0703, "output_safran/tx_france_20140929.tif") | |
writeRaster(raster_rr_0703, "output_safran/rr_france_20140929.tif") | |
# ---- exemple 3 : process grille points (1 jour, N variables, tte la France) ---- | |
pts_20180201 <- DT2sp("20140929", DT_safran) | |
st_write(pts_20180201, "output_safran/data_20140929.shp", delete_layer = T) |
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