我正在创建一些堆积的条形图，其中大约有50种不同的因素。我想要一个传说，它仅绘制8个最丰富因素的颜色。

我首先计算了平均丰度。然后我以此命令订购了该因素。并且还可以获取相应的颜色，但是我不知道是否应该“独立地”创建图例，或者是否缺少ggplot的另一种“简便”方式。 任何帮助表示赞赏。

谢谢

## calculating the OTUs mean abundance
## instead of labelling all 50 in the legend just label top 5 or 10 for label 
  meanAbund<-as.data.frame(colSums(dat.grouped[,grep("Otu",colnames(dat.grouped))]))
  meanAbund$Name<-as.character(tax_tab1[match(rownames(meanAbund),rownames(tax_tab1)),ncol(tax_tab1)])
  colnames(meanAbund)<-c("mean_abund","Name")
  top8_meanAbund<-meanAbund[rev(order(meanAbund$mean_abund)),][1:8]
# use melted dataframe for plotting      
## now ordered by mean abundance
  dat.groupedM$Level<-factor(dat.groupedM$Level,meanAbund[rev(order(meanAbund$mean_abund)),"Name"])
  #top8 (mean is greater than 0.1 %)
  # top 8 colors
  library(RColorBrewer)
  n <- length(unique(dat.groupedM$Level))
 # generate divergent color palete,cause so many colors
  qual_col_pals = brewer.pal.info[brewer.pal.info$category == 'qual',]
  col_vector = unlist(mapply(brewer.pal,qual_col_pals$maxcolors,rownames(qual_col_pals)))
  set.seed(200)
  mycols<-sample(col_vector,n)
  top8cols<-mycols[1:8]
  #pie(rep(1,n),mycols)
  ggplot(dat.groupedM,aes(x = Time,y = value,fill = Level))+
    geom_bar(stat = "identity") +
    facet_wrap(~Diet)+
   scale_fill_manual(values = mycols) +
    theme_bw()+
    theme(legend.position = "none")+
    ggtitle(paste(level,"composition - Cohort 1"))

感谢靠近，我现在有这个，见下文。但是它没有使用我之前用scale_fill_manual指定的调色板“ mycols”，现在我根据建议更改为“ mycols”。好的，现在这是正确的！

scale_fill_manual(values = mycols,breaks = top10_meanAbund$Name)+

    > dput(dat.groupedM)
structure(list(Diet = structure(c(2L,2L,3L,3L),.Label = c("Control","RC","WD"),class = "factor"),Time = structure(c(2L,"ZT2","ZT14"
),variable = structure(c(1L,1L,4L,5L,6L,7L,8L,9L,10L,11L,12L,13L,14L,15L,16L,17L,18L,19L,20L,21L,22L,23L,24L,25L,26L,27L,28L,29L,30L,31L,32L,33L,34L,35L,36L,37L,38L,39L,40L,41L,42L,43L,44L,45L,46L,47L,48L,49L,50L,50L),.Label = c("Otu1","Otu108","Otu11","Otu112","Otu136","Otu14","Otu155","Otu157","Otu158","Otu161","Otu182","Otu186","Otu197","Otu21","Otu23","Otu242","Otu244","Otu247","Otu27","Otu29","Otu30","Otu314","Otu35","Otu36","Otu378","Otu4","Otu40","Otu42","Otu427","Otu44","Otu464","Otu49","Otu53","Otu535","Otu56","Otu585","Otu607","Otu623","Otu629","Otu645","Otu648","Otu664","Otu69","Otu715","Otu730","Otu741","Otu76","Otu77","Otu86","Otu90"),value = c(0.125797907894198,0.236708006778536,0.577822547980787,0.590703405992419,0.010616635104027,0.0101758392492056,0.000833768625886666,0.00075132991625995,3.6675879491077e-05,4.75000300636826e-05,1.80354502712558e-05,7.12272349413578e-06,0.0923297961192989,0.0516121598003722,0.00943059557285678,0.0071906839719107,0.00539229454875785,0.00506484304043506,0.00338347504700533,0.0025680210124108,0.00175591025013762,0.00395104856215105,0.0561412864297836,0.0389581641347799,0.000170273382201598,0.00010844375756416,2.43702775724318e-05,2.69013349522259e-05,0.00832912099453767,0.010385453199374,0.000178806881780292,0.000192961017676232,0.000133411286157921,0.000160277350764036,3.61247330219488e-05,2.18172717187001e-05,0.0052992653709469,0.0157284378186556,1.02095850472487e-05,6.26578426928999e-06,1.60700750910741e-05,1.5642472562587e-05,6.62816031320301e-06,0.00184183762620945,0.000976314979621793,0.000837378482800852,0.00119405390180218,0.000749043101546972,2.53563183604468e-05,6.40671433657518e-05,2.15845735655314e-05,2.23193546150843e-05,0.021152108912735,0.0154293683430873,0.0179088127298003,0.0243504748685249,0.112274814726721,0.117619628857172,3.02064928526444e-05,4.05741755377207e-05,0.00181223384695308,0.00207625195815772,0.000943789542460111,0.000206467245724716,0.00154532777776536,0.00226885210972427,0.000119002475328241,0.00022113732768583,0.000235485770787934,0.000458323057092208,0.000652960109256795,0.000724862646259261,0.0727879614169974,0.0343552622468531,0.00966883214135748,0.0121723948692721,0.0502079899784375,0.0642059286182179,0.0744606748095006,0.0279356500162451,0.0165712179668264,0.0155282557608783,0.0161360297824822,0.0176198016904319,0.0025636247608102,0.0011990003339988,8.03074966867612e-05,2.33672477744522e-05,0.082133947866647,0.000268818474649765,9.9394282675768e-05,5.50800067064597e-05,0.0740561864383357,0.0623723308152442,0.0122016944534841,0.00661733731518039,0.000206774473028281,0.000181997559545235,0.000504582984323445,0.0003864059666649,0.260050134018791,0.262172946886686,0.18452199172589,0.173786000484964,0.0269969369566207,0.0314904830827211,0.00193643447967831,0.00224489247051206,3.93537896032742e-05,1.28428312370815e-05,0.0088546261393493,0.0167354308377304,1.21169704358824e-05,2.12185497965253e-05,1.43770979648094e-05,1.55017664132774e-05,4.91659313365037e-05,0.000125001966670021,6.22422609777641e-05,2.67226640566305e-05,3.7715397236691e-05,0.000156595002030591,0.000177342276671081,9.9289511018095e-05,3.26074531511788e-05,0.0133283089983016,0.016339336685079,0.000374046362264717,0.000314832095026693,0.000101840989635774,0.0499536313744285,3.07770376000906e-05,2.61927046816827e-05,0.0190857963424119,0.033561743200736,0.00670074972877479,0.00537788085712994,1.18971385403729e-05,1.11445994651961e-05,1.14712208113288e-05,2.05354865936513e-05,7.60426873897666e-06,1.20062319150955e-05,1.36539983715138e-05,7.2222843532018e-06,9.9140609239925e-06,9.94926827158573e-06,7.53483093323745e-06,8.69321376638133e-06,1.19091870744721e-05,7.23507396088365e-06,2.46118496456816e-05,2.17587837491135e-05,1.82559375344064e-05,1.89730194735652e-05,0.00660850850197291,0.0212222385456563,0.00211118341459913,0.00141420689575609,9.26797200368037e-06,8.90032999685065e-06,7.54855398500617e-06,2.23089983289096e-05,5.45457596965578e-06,5.98284905868666e-06,3.2907497931271e-05,2.32160410324433e-05,1.51092819784857e-05,7.91517227728171e-06,4.18664545392701e-05,4.14341191547126e-05,0.000151073775168509,0.000399628089283355,1.4300121286468e-05,6.26578426928999e-06),Level = structure(c(1L,22L),.Label = c("Akkermansia","Bacteroides","Pseudomonas","Anaeroplasma","Acetatifactor","Lactobacillus","Clostridium_XlVa","Oscillibacter","Eubacterium","Alistipes","Acinetobacter","Parabacteroides","Parasutterella","Bacillus","Clostridium_sensu_stricto","turicibacter","Clostridium_IV","Staphylococcus","Bifidobacterium","Romboutsia","Escherichia/Shigella","Listeria","Enterococcus","Lactococcus","flavonifractor","Ruminococcus","Lachnospiracea_incertae_sedis","Clostridium_XlVb","Stenotrophomonas","Eisenbergiella","Hungatella","Adhaeribacter","Butyricicoccus","Rhizobium","Prevotella","Intestinimonas","Sphingobium","Dorea","Enterorhabdus","Shewanella","Bradyrhizobium","Desulfovibrio","Clostridium_XVIII","Anaerostipes","Asaccharobacter","Anaerotruncus","Eggerthella","Butyricimonas","Bilophila","Anaerococcus"),class = "factor")),row.names = c(2L,52L,53L,54L,55L,57L,58L,59L,60L,62L,63L,64L,65L,67L,68L,69L,70L,72L,73L,74L,75L,77L,78L,79L,80L,82L,83L,84L,85L,87L,88L,89L,90L,92L,93L,94L,95L,97L,98L,99L,100L,102L,103L,104L,105L,107L,108L,109L,110L,112L,113L,114L,115L,117L,118L,119L,120L,122L,123L,124L,125L,127L,128L,129L,130L,132L,133L,134L,135L,137L,138L,139L,140L,142L,143L,144L,145L,147L,148L,149L,150L,152L,153L,154L,155L,157L,158L,159L,160L,162L,163L,164L,165L,167L,168L,169L,170L,172L,173L,174L,175L,177L,178L,179L,180L,182L,183L,184L,185L,187L,188L,189L,190L,192L,193L,194L,195L,197L,198L,199L,200L,202L,203L,204L,205L,207L,208L,209L,210L,212L,213L,214L,215L,217L,218L,219L,220L,222L,223L,224L,225L,227L,228L,229L,230L,232L,233L,234L,235L,237L,238L,239L,240L,242L,243L,244L,245L,247L,248L,249L,250L),class = "data.frame")