[R] depth of labels of axis

David Winsemius dwinsemius at comcast.net
Thu Sep 4 21:24:50 CEST 2014

On Sep 3, 2014, at 10:05 PM, Jinsong Zhao wrote:

> On 2014/9/3 21:33, Jinsong Zhao wrote:
>> On 2014/9/2 11:50, David L Carlson wrote:
>>> The bottom of the expression is set by the lowest character (which can
>>> even change for subscripted letters with descenders. The solution is
>>> to get axis() to align the tops of the axis labels and move the line
>>> up to reduce the space, e.g.
>>> plot(1:5, xaxt = "n")
>>> axis(1, at = 1:5, labels = c(expression(E[g]), "E", expression(E[j]),
>>> "E", expression(E[t])), padj=1, mgp=c(3, .1, 0))
>>> # Check alignment
>>> abline(h=.7, xpd=TRUE, lty=3)
>> yes. In this situation, padj = 1 is the fast solution. However, If there
>> are also superscript, then it's hard to alignment all the labels.
>> If R provide a mechanism that aligns the label in axis() or text() with
>> the baseline of the character without the super- and/or sub-script, that
>> will be terrific.
> it seems that the above wish is on the Graphics TODO lists:
> https://www.stat.auckland.ac.nz/~paul/R/graphicstodos.html
> Allow text adjustment for mathematical annotations which is relative to a text baseline (in addition to the current situation where adjustment is relative to the bounding box).

In many case adding a phantom argument will correct aliognment problems:

plot(1:5, xaxt = "n")
axis(1, at = 1:5, labels = c(expression(E[g]), E~phantom(E[g]), expression(E[j]),
E~phantom(E[g]), expression(E[t])))

abline(h=.7, xpd=TRUE, lty=3)

Notice that c(expression(.), ...) will coerce all items separated by commas to expressions, sot you cna just put in "native" expression that are not surrounded by the `expression`-function

c(expression(E[g]), E~phantom(E[g]), expression(E[j])  ) #returns
# expression(E[g], E ~ phantom(E[g]), E[j])

The tilde is actually a function that converts parse-able strings into R language objects:

c(expression(E[g]), E~phantom(E[g]), ~E[j])


>>> -----Original Message-----
>>> From: r-help-bounces at r-project.org
>>> [mailto:r-help-bounces at r-project.org] On Behalf Of Jinsong Zhao
>>> Sent: Monday, September 1, 2014 6:41 PM
>>> To: r-help at r-project.org
>>> Subject: [R] depth of labels of axis
>>> Hi there,
>>> With the following code,
>>> plot(1:5, xaxt = "n")
>>> axis(1, at = 1:5, labels = c(expression(E[g]), "E", expression(E[j]),
>>> "E", expression(E[t])))
>>> you may notice that the "E" within labels of axis(1) are not at the same
>>> depth. So the vision of axis(1) labels is something like wave.
>>> Is there a possible way to typeset the labels so that they are have the
>>> same depth?
>>> Any suggestions will be really appreciated. Thanks in advance.
>>> Best regards,
>>> Jinsong

David Winsemius
Alameda, CA, USA

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