[英]Subscript in plot title in r
我想补充标题“1999年至2008年美国PM2.5的排放”,该标题使用r中的基础绘图功能。 在那,我希望2.5成为PM的下标。 如果PM2.5恰好位于字符串的末尾,我没有任何问题:
barplot(height = total.emissions$Emissions, names.arg=total.emissions$year,
xlab="Year", ylab= " Amount of emitted in tonsPM"2.5 ,
main = "Emissions from in the United States from 1999 to 2008PM"[2.5] )
但如果它在字符串的中间,我就不能这样做。 如果我把它分成两部分,如下:
barplot(height = total.emissions$Emissions, names.arg=total.emissions$year,
xlab="Year", ylab= " Amount of PM_[2.5] emitted in tons",
main = expression("Emissions from PM"[2.5] "in the United States from 1999 to 2008"))
由于方括号,我收到错误说出意外的符号。
尝试使用paste
函数进行expression
(有关详细信息,请参阅?plotmath
),例如:
plot(0, main = expression(paste("Emissions from ", PM[2.5], " in the United States from 1999 to 2008")))
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