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I have a vectors of strings, say c("E^A","S^P","lambda","T","E^Q","E^Q","AT"), and I want to plot them as the x axis label using math expression. (I believe I have written them in math expression format, but with quote)
When I put
text(x,par("usr")[3]-0.2,labels=substitute(A,list(A=label)),srt=20,pos=1,adj = c(1.1,1.1), xpd = TRUE,cex=0.7)
The x axis only shows "E^A","S^P","lambda","T","E^Q","E^Q","AT", not the mathematical interpretation of the strings, and I guess it's because they are not regarded as math symbols.
How can I get mathematical labeling then? Thanks so much!
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Convert a String to an Expression in R Programming – parse() Function. parse() function in R Language is used to convert an object of character class to an object of expression class.
Math inside RMarkdownIn side a text chunk, you can use mathematical notation if you surround it by dollar signs $ for “inline mathematics” and $$ for “displayed equations”. Do not leave a space between the $ and your mathematical notation. Example: $\sum_{n=1}^{10} n^2$ is rendered as ∑10n=1n2.
You can use the built-in Python eval() to dynamically evaluate expressions from a string-based or compiled-code-based input. If you pass in a string to eval() , then the function parses it, compiles it to bytecode, and evaluates it as a Python expression.
In general, use expression (see ?plotMath):
plot(1,main=expression(E^A))
Note that the 'E^A' is not in quote marks.
To generate expressions from a character vector, use parse(text=...):
lbls <- c("E^A","S^P","lambda","T","E^Q","E^Q","AT")
x <- 1:length(lbls)
y <- runif(length(lbls))
# I'm just going to draw labels on the (x,y) points.
plot(x,y,'n')
text(x,y, labels=parse(text=lbls)) # see the parse(text=lbls) ?
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