如何用ggplot2在y = 0軸上居中x軸標籤？

Question

我有下述R代碼：

library("ggplot2") 

x=read.table('some_file') 

df <- data.frame(V1 = x$V1, V2 = x$V2) 

jpeg('file.jpg',width=1600,height=800) 
ggplot(df, aes(x=as.numeric(row.names(df)), y=V1)) + 
    geom_bar(stat="identity", fill="grey", width=0.7) + 
    geom_errorbar(aes(ymin = V1 - V2, ymax = V1 + V2), width=0.5) + 
    scale_x_continuous(breaks=c(1,seq(1,length(x$V1),1)), expand=c(0,0)) + 
    theme(axis.text.x=element_text(size = 9, angle = 90, vjust = 0.5, hjust=8.5)) + xlab("position") + ylab("Y axis") + labs(title = "Title") 
dev.off 

我所需要的x軸的標籤，即，數字1,2,3 ...趴在y = 0的軸或略低於它。我嘗試過玩弄，但無論我用什麼樣的價值，它都不太合適。例如，當hjust = 8.5時，從100到167的數字就是我需要它們的數字，但之前的數字比y = 0軸高出很多。

任何人都可以幫忙嗎？這裏是兩個列向量的問題：

-0.11285825 0.0134043866 
-0.00427275 0.0012140211 
-0.00825875 0.0025256419 
-0.08434275 0.0153227983 
0.111627 0.0149667631 
-0.00591775 0.0028993564 
-0.00710475 0.0014442042 
-0.00660175 0.0005508105 
0.1259935 0.0176350505 
-0.02468425 0.0049306177 
-0.0046885 0.0005749567 
-0.002225 0.0009090044 
-0.01276025 0.0040398386 
-0.11821675 0.0699125335 
-0.0035805 0.0010421268 
-0.00276825 0.0011773666 
-0.014487 0.0004579208 
-0.06269425 0.0181558159 
-0.0028185 0.0004570594 
0.00163075 0.0004970686 
-0.003703 0.0005301641 
-0.0059895 0.00101644 
-0.00164725 0.0005756263 
-0.001748 0.0008530894 
-0.00265675 0.0001855982 
0.0617135 0.0148209217 
-0.20685225 0.0116178605 
0.001209 0.0015875276 
-0.000297 0.0006022711 
0.00447675 0.0012625121 
-0.00088225 0.0040488959 
-0.1444145 0.0142768668 
-0.01167825 0.0012083802 
0.01813575 0.0031464967 
-0.007798 0.0106417775 
-0.18151 0.0073565153 
0.36773125 0.0181246164 
0.562059 0.1015533768 
-0.00886525 0.0131807785 
0.174133 0.0431058507 
0.57896425 0.2444875207 
-0.8418545 0.138881625 
0.02951775 0.0654937622 
-0.12007175 0.034225026 
-1.6405275 0.5553336954 
-1.88679875 0.7850254112 
-0.231041 0.0164808312 
-0.1266595 0.0617940077 
-0.19167575 0.0507706792 
-1.055467 0.4429050182 
-0.116364 0.0357189981 
-0.19901725 0.0509971349 
-1.7670315 0.1542821762 
-0.10039375 0.0352431413 
-0.11883575 0.0114192525 
-0.3665885 0.1246847809 
-1.9132725 0.5623975368 
-0.31451275 0.1145112995 
-0.11942425 0.0375176069 
-0.04436425 0.0204052159 
-0.0098315 0.0023110857 
-0.007022 0.0030733554 
-0.1755365 0.1161738267 
-0.081695 0.0216418659 
-0.06446825 0.006684648 
-0.5098405 0.5403101751 
-0.05826375 0.1454962774 
-0.28179575 0.0358286362 
-0.201353 0.0584529251 
-0.7666615 0.143889849 
-3.36481375 0.2914767538 
-0.358104 0.0669525527 
-0.17513975 0.0110406376 
-3.76037275 0.7028178063 
-2.91671325 0.0631300928 
-0.382157 0.0164434459 
0.28983275 0.1447389319 
-0.1522485 0.6711400536 
-0.21333325 0.0195889096 
-0.135311 0.019034877 
-2.54135775 0.1089711993 
-1.02318925 0.096562207 
-1.52091 0.1405089663 
-9.649117 0.2311164764 
-0.36733 0.0339848999 
-0.89744525 0.0296846006 
-0.69533325 0.0863715014 
-0.30171975 0.0261684616 
-0.0915285 0.0101355205 
0.11442675 0.0466793911 
-1.05659675 0.1963164192 
-0.01967525 0.0056679875 
0.00163325 0.0047527004 
-0.008276 0.035198076 
-0.070888 0.0277879036 
0.0003515 0.0048609681 
-0.00769575 0.0051084448 
-0.0628 0.0277348014 
-0.00517225 0.0050401386 
-0.002678 0.0015185852 
0.000215 0.0106790497 
0.0303 0.0148194041 
0.0157995 0.0098726426 
-0.01274725 0.0026780256 
-0.00394375 0.0006370312 
0.00103025 0.0003137287 
-0.00834475 0.0004048057 
-0.010351 0.0012089266 
-0.00144675 0.0003594665 
-0.019411 0.0143840738 
-0.01995875 0.0014986806 
-0.00944875 0.0008936362 
-0.00012 0.0001115437 
-0.017019 0.0007678965 
-0.0146025 0.0058825609 
-0.00330075 0.000519175 
0.0034255 0.001374384 
-0.03580625 0.0039048393 
-0.0008405 0.0010331095 
0.006152 0.000903144 
0.08482425 0.0169920168 
0.013677 0.0030233132 
-0.00002725 0.0015909331 
0.15528725 0.0129757832 
0.0062995 0.000357788 
-0.0886525 0.0078460151 
0.01510875 0.0010974966 
0.00863325 0.0004734867 
0.32934625 0.0152748957 
0.067786 0.0029502796 
0.00300625 0.0004219979 
0.04193375 0.0018489418 
-0.0000245 0.009160398 
0.3010235 0.0192036334 
-0.01484775 0.0286606604 
-0.183226 0.050428693 
-0.026292 0.005153877 
0.53286075 0.050951844 
-1.5150745 0.2209543557 
0.2785605 0.0408203229 
0.4550995 0.027406819 
-0.3947985 0.4327885451 
0.23381825 0.2238431016 
-0.22846625 0.0188915484 
-0.31804825 0.2029861787 
-1.7850215 0.5281493487 
-1.67640075 0.2481773479 
-0.661103 0.0595275708 
-4.67910175 1.0021441745 
-0.22585775 0.2284251402 
0.4079195 0.2637898013 
-0.82208 0.1246448589 
-3.8169575 0.2426232257 
-5.66482025 0.5167259264 
-0.65876175 0.1498171905 
-3.275229 0.4303526931 
-0.80324675 0.11413495 
-2.2098325 0.1510774807 
-0.8855575 0.6300580366 
-4.4606575 0.2082186001 
0.95024225 0.1393782289 
-0.26379 0.0212151113 
-0.436935 0.1433744083 
-2.34355175 0.0412962458 
0.60204025 0.0836441211 
-0.16453425 0.0148762548 
0.4368215 0.1924153651 

Answer 1

手動放置會給你完全控制。另外，x已經是data.frame read.table()產生data.frames。

library(ggplot2) 

df <- read.table('somefile') 

jpeg('file.jpg',width=1600,height=800) 
gg <- ggplot(df, aes(x=as.numeric(row.names(df)), y=V1)) 
gg <- gg + geom_bar(stat="identity", fill="grey", width=0.7) 
gg <- gg + geom_errorbar(aes(ymin = V1 - V2, ymax = V1 + V2), width=0.5) 
gg <- gg + geom_text(data=data.frame(x=1:length(df$V1)), 
        aes(x=x, y=0, label=x), size=2.5, angle=90, hjust=0) 
gg <- gg + scale_x_continuous(expand=c(0,0)) 
gg <- gg + labs(x="position", y="Y axis", title="Title") 
gg <- gg + theme(axis.ticks.x=element_blank()) 
gg <- gg + theme(axis.text.x=element_blank()) 
gg 
dev.off() 
system("open file.jpg")