[R] curve() doesn't seem to use the whole range of x? And Error: longer object length is not a multiple of shorter object length
mviljamaa
mviljamaa at kapsi.fi
Sun Sep 25 18:04:09 CEST 2016
On 2016-09-25 18:52, Jeff Newmiller wrote:
> You seem to be confused about what curve is doing vs. what you are
> doing.
But my x-range in curve()'s parameters from and to should be the entire
lka vector, since they are from=min(lka) and to=max(lka). Then why does
this not span the entire of lka? Because of duplicate entries or what?
It seems like I cannot use curve(), since my x-axis must be exactly lka
for the function to plot the y value for every lka value.
> A) Compute the points you want to plot and put them into 2 vectors.
> Then figure out how to plot those vectors. Then (perhaps) consider
> putting that all into one line of code again.
>
> B) The predict function is the preferred way to compute points. It may
> be educational for you to do the computations by hand at first, but in
> the long run using predict will help you avoid problems getting the
> equations right in multiple places in your script.
>
> C) Learn what makes an example reproducible (e.g. [1] or [2]), and ask
> your questions with reproducible code and data so we can give you
> concrete responses.
>
> [1] http://adv-r.had.co.nz/Reproducibility.html
> [2]
> http://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example
> --
> Sent from my phone. Please excuse my brevity.
>
> On September 25, 2016 8:36:49 AM PDT, mviljamaa <mviljamaa at kapsi.fi>
> wrote:
>> On 2016-09-25 18:30, Duncan Murdoch wrote:
>>> On 25/09/2016 9:10 AM, Matti Viljamaa wrote:
>>>> Writing:
>>>>
>>>>
>> bs["(Intercept)"]+bs["mies"]*0+bs["kouluB"]+bs["lka"]*lka+bs["kouluB:clka"]*clka
>>>>
>>>> i.e. without that being inside curve produces a vector of length
>> 375.
>>>>
>>>> So now it seems that curve() is really skipping some lka-/x-values.
>>>
>>> How could curve() know what the length of lka is? You're telling it
>>> to set x to a sequence of values of length 101 (the default) from
>>> min(lka) to max(lka). You never tell it to set x to lka.
>>>
>>> curve() is designed to plot expressions or functions, not vectors.
>> If
>>> you actually want to plot line segments using your original data, use
>>> lines(). (You'll likely need to sort your x values into increasing
>>> order if you do that, or you'll get a pretty ugly plot.)
>>>
>>> Duncan Murdoch
>>
>> I know that about curve(), but since this function uses lka as a
>> parameter, then how should I formulate it for curve so that I don't
>> get
>>
>> the error about wrong lengths?
>>
>>>>
>>>>> On 25 Sep 2016, at 16:01, Matti Viljamaa <mviljamaa at kapsi.fi>
>> wrote:
>>>>>
>>>>> I’m trying to plot regression lines using curve()
>>>>>
>>>>> The way I do it is:
>>>>>
>>>>> bs <- coef(fit2)
>>>>>
>>>>> and then for example:
>>>>>
>>>>>
>> curve(bs["(Intercept)"]+bs["mies"]*0+bs["kouluB"]+bs["lka"]*x+bs["kouluB:clka"]*clka,
>>
>>>>> from=min(lka), to=max(lka), add=TRUE, col='red')
>>>>>
>>>>> This above code runs into error:
>>>>>
>>>>> Error in curve(bs["(Intercept)"] + bs["mies"] * 0 + bs["kouluB"] +
>>>>> bs["lka"] * :
>>>>> 'expr' did not evaluate to an object of length 'n'
>>>>> In addition: Warning message:
>>>>> In bs["(Intercept)"] + bs["mies"] * 0 + bs["kouluB"] + bs["lka"] *
>> :
>>>>> longer object length is not a multiple of shorter object length
>>>>>
>>>>> Which I’ve investigated might be related to the lengths of the
>>>>> different objects being multiplied or summed.
>>>>> Taking length(g$x) or length(g$y) of
>>>>>
>>>>> g <- curve(bs["(Intercept)"]+bs["mies"]*0+bs["kouluB"]+bs["lka"]*x,
>>
>>>>> from=min(lka), to=max(lka), add=TRUE, col='red')
>>>>>
>>>>> returns 101.
>>>>>
>>>>> However length(lka) is 375. But perhaps these being different is
>> not
>>>>> the problem?
>>>>>
>>>>> I however do see that the whole range of lka is not plotted, for
>> some
>>>>> reason. So how can I be sure
>>>>> that it passes through all x-values in lka? And i.e. that the
>> lengths
>>>>> of objects inside curve() are correct?
>>>>>
>>>>> What can I do?
>>>>
>>>> ______________________________________________
>>>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>>> PLEASE do read the posting guide
>>>> http://www.R-project.org/posting-guide.html
>>>> and provide commented, minimal, self-contained, reproducible code.
>>>>
>>
>> ______________________________________________
>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide
>> http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
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