# [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 17:36:49 CEST 2016

```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

>>
>>> 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,
>>>
>>> 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 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,
>>>
>>> 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?
>>
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