I have a series of plots showing environmental pollution obtained with this code :
data$Nuc[grepl("Ag-|H-3|Mn-|Am-241|Co-|Cs-|Pu-|Tc-99|Sr-90", data$Nuclides)] <- 'Artificial nuclides'
data$Nuc[!grepl("Ag-|H-3|Mn-|Am-241|Co-|Cs-|Pu-|Tc-99|Sr-90", data$Nuclides)] <- 'Natural nuclides'
data_l <- split(data,list(data$Sample.type), drop=TRUE)
lapply(names(data_l), function(i){
ggplot(data_l[[i]], aes(Date, Activity, group = Nuclides, col = as.factor(Nuclides)))+
colorization +
geom_line() + scale_x_date(labels = date_format("%Y"), date_breaks = "1 year", limits = c(min(data$Date), max(data$Date))) +
geom_point() +
facet_grid(cols = vars(Nuc), rows = vars(Locality.Name), scales = "fixed") +
xlab("Date") +
ylab(paste("Activity concentrations in", data_l[[ i ]]$Unit[ 1 ])) +
theme(legend.title=element_blank(),
strip.text.x = element_text(size = 12, colour = "black"),
strip.text.y = element_text(size = 12, colour = "black"),
legend.text = element_text(size = 12)) +
guides(col=guide_legend(ncol=1)) +
ggsave(paste(i, ".png", sep = ""), dpi = 400, width = 30, height = 20, units = "cm")
})dev.off()
which gives :
The legend, alphabetically classified, is quite hard to follow for people who do not work in the field of radioactivity and do not know which radionuclide is of natural origin and which one is an anthropogenic one.
For clarity reason, I wish to divide the legend in 2 parts : "Natural nuclides" and "Artificial nuclides" in the same way the plot is currently divided in two columns with facet_grid
I read an explanation in ggplot2: Divide Legend into Two Columns, Each with Its Own Title but it did not work in my case.
Any ideas of how to "split" the legend ?
EDIT : To help you, I give you some data using head(data, 60)
> head(data, 60)
Sample.type Locality.Name Nuclides Date Activity Uncertainty Unit Nuc
144 North Sea aquatic plants OOSTENDE Ra-226 2010-07-01 1.3892770 1.0103840 Bq/kg Natural nuclides
167 North Sea fish NORTH SEA Th-228 2010-10-01 0.3324930 0.1899960 Bq/kg Natural nuclides
379 Freshwater aquatic plants MOL-GEEL Be-7 2010-11-02 6.8424231 2.8810202 Bq/kg Natural nuclides
380 Freshwater aquatic plants MOL-GEEL Cs-137 2010-11-02 0.8282933 0.3601275 Bq/kg Artificial nuclides
478 Oysters Scheldt HOOFDPLAAT-KLOOSTERZANDE Th-228 2010-03-03 0.4243410 0.1795290 Bq/kg Natural nuclides
482 North Sea aquatic plants HOOFDPLAAT-KLOOSTERZANDE Be-7 2010-03-03 2.2304610 1.3940381 Bq/kg Natural nuclides
483 North Sea aquatic plants HOOFDPLAAT-KLOOSTERZANDE Ra-228 2010-03-03 1.3940380 0.6970191 Bq/kg Natural nuclides
484 North Sea aquatic plants HOOFDPLAAT-KLOOSTERZANDE Th-228 2010-03-03 0.5157940 0.2927480 Bq/kg Natural nuclides
485 North Sea aquatic plants HOOFDPLAAT-KLOOSTERZANDE Ra-226 2010-03-03 1.7983090 0.2648672 Bq/kg Natural nuclides
486 North Sea aquatic plants HOOFDPLAAT-KLOOSTERZANDE Am-241 2010-03-03 2.3838050 0.4879133 Bq/kg Artificial nuclides
519 Freshwater aquatic mosses AMPSIN-FLÉMALLE Be-7 2010-06-03 66.2000000 34.3000000 Bq/kg Natural nuclides
522 Freshwater aquatic mosses AMPSIN-FLÉMALLE Co-60 2010-06-03 4.0900000 1.7400000 Bq/kg Artificial nuclides
523 Freshwater aquatic mosses AMPSIN-FLÉMALLE I-131 2010-06-03 20.9000000 4.9500000 Bq/kg Artificial nuclides
524 Freshwater aquatic mosses AMPSIN-FLÉMALLE Ra-226 2010-06-03 7.8200000 3.3800000 Bq/kg Natural nuclides
525 Freshwater aquatic mosses AMPSIN-FLÉMALLE Ra-228 2010-06-03 22.1000000 5.5800000 Bq/kg Natural nuclides
526 Freshwater aquatic mosses AMPSIN-FLÉMALLE Th-228 2010-06-03 11.1000000 4.8600000 Bq/kg Natural nuclides
527 Freshwater aquatic mosses ANDENNE (GIVES) Be-7 2010-06-03 193.0000000 63.7000000 Bq/kg Natural nuclides
529 Freshwater aquatic mosses ANDENNE (GIVES) I-131 2010-06-03 47.2000000 21.1000000 Bq/kg Artificial nuclides
530 Freshwater aquatic mosses ANDENNE (GIVES) Ra-228 2010-06-03 63.0000000 19.7000000 Bq/kg Natural nuclides
531 Freshwater aquatic mosses ANDENNE (GIVES) Th-228 2010-06-03 18.9000000 12.1000000 Bq/kg Natural nuclides
532 Freshwater aquatic mosses AMPSIN-FLÉMALLE Be-7 2010-06-03 208.0000000 35.5000000 Bq/kg Natural nuclides
534 Freshwater aquatic mosses AMPSIN-FLÉMALLE I-131 2010-06-03 11.5000000 8.8600000 Bq/kg Artificial nuclides
535 Freshwater aquatic mosses AMPSIN-FLÉMALLE Ra-226 2010-06-03 17.7000000 6.2200000 Bq/kg Natural nuclides
536 Freshwater aquatic mosses AMPSIN-FLÉMALLE Th-228 2010-06-03 19.7000000 6.8800000 Bq/kg Natural nuclides
537 Freshwater aquatic mosses FLORIFFOUX-MORNIMONT-SAMBREVILLE Be-7 2010-06-03 130.0000000 44.7000000 Bq/kg Natural nuclides
539 Freshwater aquatic mosses FLORIFFOUX-MORNIMONT-SAMBREVILLE Ra-226 2010-06-03 34.2000000 6.8400000 Bq/kg Natural nuclides
540 Freshwater aquatic mosses FLORIFFOUX-MORNIMONT-SAMBREVILLE Th-228 2010-06-03 33.7000000 6.0800000 Bq/kg Natural nuclides
541 Freshwater aquatic mosses HUY Be-7 2010-06-03 97.5000000 18.7000000 Bq/kg Natural nuclides
543 Freshwater aquatic mosses HUY I-131 2010-06-03 11.2000000 4.1900000 Bq/kg Artificial nuclides
544 Freshwater aquatic mosses HUY Cs-137 2010-06-03 3.3300000 0.9490000 Bq/kg Artificial nuclides
545 Freshwater aquatic mosses HUY Ra-226 2010-06-03 19.4000000 2.4300000 Bq/kg Natural nuclides
546 Freshwater aquatic mosses HUY Ra-228 2010-06-03 31.0000000 4.0300000 Bq/kg Natural nuclides
547 Freshwater aquatic mosses HUY Th-228 2010-06-03 21.9000000 2.5600000 Bq/kg Natural nuclides
548 Freshwater aquatic mosses VISÉ (LIXHE) Be-7 2010-06-03 203.0000000 30.9000000 Bq/kg Natural nuclides
550 Freshwater aquatic mosses VISÉ (LIXHE) Co-60 2010-06-03 3.0100000 1.8100000 Bq/kg Artificial nuclides
551 Freshwater aquatic mosses VISÉ (LIXHE) I-131 2010-06-03 22.5000000 6.8600000 Bq/kg Artificial nuclides
552 Freshwater aquatic mosses VISÉ (LIXHE) Cs-137 2010-06-03 4.6700000 2.6400000 Bq/kg Artificial nuclides
553 Freshwater aquatic mosses VISÉ (LIXHE) Ra-226 2010-06-03 23.7000000 4.0500000 Bq/kg Natural nuclides
554 Freshwater aquatic mosses VISÉ (LIXHE) Ra-228 2010-06-03 48.3000000 9.0800000 Bq/kg Natural nuclides
555 Freshwater aquatic mosses VISÉ (LIXHE) Th-228 2010-06-03 22.8000000 4.2500000 Bq/kg Natural nuclides
556 Freshwater aquatic plants AMPSIN-FLÉMALLE Be-7 2010-06-03 99.3000000 9.6400000 Bq/kg Natural nuclides
558 Freshwater aquatic plants AMPSIN-FLÉMALLE Cs-137 2010-06-03 0.7660000 0.3580000 Bq/kg Artificial nuclides
559 Freshwater aquatic plants ANDENNE (GIVES) Be-7 2010-06-03 49.8000000 14.4000000 Bq/kg Natural nuclides
561 Freshwater aquatic plants ANDENNE (GIVES) Th-228 2010-06-03 5.3400000 3.5200000 Bq/kg Natural nuclides
562 Freshwater aquatic plants HUY Be-7 2010-06-03 60.7000000 9.7700000 Bq/kg Natural nuclides
564 Freshwater aquatic plants HUY Th-228 2010-06-03 1.6700000 1.5400000 Bq/kg Natural nuclides
565 Freshwater aquatic plants VISÉ (LIXHE) Be-7 2010-06-03 174.0000000 19.8000000 Bq/kg Natural nuclides
601 Freshwater aquatic mosses ANDENNE (GIVES) Be-7 2010-09-03 68.1000000 35.9000000 Bq/kg Natural nuclides
603 Freshwater aquatic mosses ANDENNE (GIVES) Cs-137 2010-09-03 3.2300000 1.6300000 Bq/kg Artificial nuclides
604 Freshwater aquatic mosses ANDENNE (GIVES) Ra-226 2010-09-03 35.2000000 2.5400000 Bq/kg Natural nuclides
605 Freshwater aquatic mosses ANDENNE (GIVES) Ra-228 2010-09-03 34.4000000 4.4800000 Bq/kg Natural nuclides
606 Freshwater aquatic mosses ANDENNE (GIVES) Th-228 2010-09-03 33.8000000 3.0500000 Bq/kg Natural nuclides
607 Freshwater aquatic mosses HUY Be-7 2010-09-03 490.0000000 86.0000000 Bq/kg Natural nuclides
609 Freshwater aquatic mosses HUY Cs-137 2010-09-03 11.7000000 5.0400000 Bq/kg Artificial nuclides
610 Freshwater aquatic mosses HUY Ra-226 2010-09-03 25.3000000 6.9000000 Bq/kg Natural nuclides
611 Freshwater aquatic mosses HUY Th-228 2010-09-03 15.0000000 9.7300000 Bq/kg Natural nuclides
612 Freshwater aquatic plants AMPSIN-FLÉMALLE Be-7 2010-09-03 343.0000000 33.0000000 Bq/kg Natural nuclides
614 Freshwater aquatic plants AMPSIN-FLÉMALLE Ra-226 2010-09-03 2.5700000 0.8600000 Bq/kg Natural nuclides
615 Freshwater aquatic plants AMPSIN-FLÉMALLE H-3 2010-09-03 83.0800000 8.9400000 Bq/kg Artificial nuclides
616 Freshwater aquatic plants ANDENNE (GIVES) Be-7 2010-09-03 98.2000000 26.3000000 Bq/kg Natural nuclides
