此代码在ggplot中生成一个条形图：
ggplot(res, aes(x=TOPIC,y=count), labs(x=NULL)) +
scale_y_continuous(limits=c(0,130),expand=c(0,0)) +
scale_x_discrete("",labels=c("ANA"="Anatomy","BEH"="Behavior","BOUND"="Pop boundaries",
"CC"="Climate change","DIS"="Disease","EVO"="Evolution",
"POPSTAT"="Pop status","POPABU"="Pop abundance",
"POPTR"="Pop trend","HARV"="Harvest","HAB"="Habitat",
"HABP"="Habitat protection","POLL"="Pollution",
"ZOO"="Captivity","SHIP"="Shipping","TOUR"="Tourism",
"REPEC"="Reprod ecology","PHYS"="Physiology","TEK"="TEK",
"HWC"="HWC","PRED"="Predator-prey","METH"="Methods",
"POPGEN"="Pop genetics","RESIMP"="Research impact",
"ISSUE"="Other","PROT"="Protection","PA"="Protected areas",
"PEFF"="Protection efficiency","MINOR"="Minor","REV"="Review")) +
theme_bw(base_size = 14) +
theme(axis.text.x=element_text(angle=90,hjust=1,vjust=0.3)) +
geom_bar(stat='identity') +
ggtitle("Peer-reviewed papers per topic")
这是数据框：
structure(list(TOPIC = structure(c(20L, 18L, 21L, 3L, 9L, 4L,
7L, 8L, 17L, 27L, 29L, 2L, 24L, 30L, 16L, 28L, 10L, 22L, 12L,
5L, 1L, 19L, 6L, 25L, 11L, 23L, 14L, 15L, 13L, 26L), .Label = c("ANA",
"BEH", "BOUND", "CC", "DIS", "EVO", "HAB", "HABP", "HARV", "HWC",
"ISSUE", "METH", "MINOR", "PA", "PEFF", "PHYS", "POLL", "POPABU",
"POPGEN", "POPSTAT", "POPTR", "PRED", "PROT", "REPEC", "RESIMP",
"REV", "SHIP", "TEK", "TOUR", "ZOO"), class = "factor"), count = c(9,
7, 13, 5, 23, 35, 27, 5, 118, 0, 9, 22, 29, 46, 27, 12, 9, 44,
70, 40, 24, 19, 26, 2, 4, 17, 4, 10, 86, 31)), .Names = c("TOPIC",
"count"), row.names = c(NA, -30L), class = "data.frame")
如何按条数排序，减少或增加？