I just found out that my "does this by default" statement (by which I was
referring to the ability to automatically connect two points with a NA in the
middle in a time series) is wrong! Actually, all plotting functions, i.e.
plot, matplot and xyplot, don't plot NAs. The solution I came up with is
convert the data to "long" table, remove NAs, and then use xyplot. See example
below:
set.seed(1234)
a=b=matrix(rnorm(9), 3,3)
b[2,2]=NA
matplot(a, type="b")
matplot(b, type="b") ## I want the two "2" connected!
matplot(b, type="l") ## Now my data for the second column are missing from the
graph
## my solution
tmp1 <- data.frame(g=rep(1:3,each=3), x=rep(1:3,3), y=c(b))
xyplot(y~x, group=g, data=tmp1, type="b", pch=c("1","2","3")) ## there is
still no line connecting two "2"s.
tmp2 <- tmp1[!is.na(tmp1$y),]
xyplot(y~x, group=g, data=tmp2, type="b")
## this is what I want, b/c it's easier for me to keep track of both trend and
missing values. The original post was really asking whether a simple change of
some parameters in matplot can do this. Now, I guess not.
...Tao
----------------------------------------
> From: maech...@stat.math.ethz.ch
> Date: Thu, 6 May 2010 18:34:22 +0200
> To: shi...@hotmail.com
> CC: ggrothendi...@gmail.com; r-help@r-project.org
> Subject: Re: [R] 'matplot' for matrix with NAs: broken lines
>
>>>>>> "TS" == Tao Shi
>>>>>> on Wed, 5 May 2010 20:11:26 +0000 writes:
>
> TS> Thanks, Gabor! So, there is no way I can change some graphic parameters
> in 'matplot' to get this?
>
>
> TS> I forgot to mention that I purposely use type="b", so I know where the
> missing data are. With imputed data, either using "b" or "l", there is no
> way to keep track of NAs. Plus, in my real data sometimes there is only one
> non-missing value in a particular column and na.approx can't work (well I
> could selectively impute the NAs ... )
>
> TS> So far, my best solution to this is to use "xyplot". It does this by
> default, but of course I need some data manipulation first.
>
> "does this by default" meaning what?
> I don't think it does impute missing, does it?
>
> Can you elaborate, using your example (below)?
>
> I found Gabor's answer appropriate,
> I really cannot see why matplot() should behave differently here...
>
> ----
>
> Martin Maechler
>
>
>
>
> TS> ----------------------------------------
>>> From: ggrothendi...@gmail.com
>>> Date: Wed, 5 May 2010 15:45:44 -0400
>>> Subject: Re: [R] 'matplot' for matrix with NAs: broken lines
>>> To: shi...@hotmail.com
>>> CC: r-help@r-project.org
>>>
>>> Try this:
>>>
>>> library(zoo)
>>> matplot(na.approx(b), type = "l")
>>>
>>> On Wed, May 5, 2010 at 2:30 PM, Tao Shi wrote:
>>>>
>>>> Hi list,
>>>>
>>>> I know that points involving NAs are not plotted in 'matplot', but when I
>>>> plot them as lines, I still want the lines to connect all the points (i.e.
>>>> not broken where there are NAs). Please see the example below. How can I
>>>> achieve this in 'matplot'? If I can't, any good alternatives so I don't
>>>> have to use 'plot' + 'lines' and loop through all the columns.
>>>>
>>>> Many thanks!
>>>>
>>>> ...Tao
>>>>
>>>>> set.seed(1234)
>>>>> a=b=matrix(rnorm(9), 3,3)
>>>>> b[2,2]=NA
>>>>> matplot(a, type="b")
> TS> [[elided Hotmail spam]]
>>>>> matplot(b, type="l") ## Now my data for the second column are missing
>>>>> from the graph
>>>>
>>>>
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>>>>
>
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