Ok,many thanks for your detailed answer.








At 2013-09-18 19:20:26,"Duncan Murdoch" <murdoch.duncan@gmail.com> wrote:
>On 13-09-18 1:38 AM, meng wrote:
>> Oh,yes, I found out this according to your reply.Thanks.
>>
>> As to time series analysis, in order to show the effect of smoothing or
>> filtering,the common command is:
>> plot(ts0);
>> lines(fitted(...))
>> But not "lines(fitted(...) ~ time(ts) )"
>>
>> How to understand this then?
>
>lines() and plot() are "generic functions".  What it does depends on the 
>class of the first argument.   To see what happens, you need to know the 
>class of ts0, or fitted(...), or fitted(...) ~ time(ts).  I'd guess ts0 
>has some time series class, fitted(...) probably has class "numeric" 
>(though this would depend on the dots, since it is also generic), and 
>the formula has class "formula".    "numeric" generally gets the default 
>method (plot.default, lines.default); "formula" usually has its own 
>methods (plot.formula, lines.formula), etc.  Read up on this in An 
>Introduction to R for more details (sections 3.4 and 10.9).
>
>Duncan Murdoch
>
>>
>> Many thanks.
>>
>> Best.
>>
>>
>>
>>
>> At 2013-09-18 08:49:51,"Duncan Murdoch" <murdoch.duncan@gmail.com> wrote:
>>>On 13-09-17 6:36 PM, meng wrote:
>>>> Thanks for your reply.
>>>>
>>>> Is "fitted(lm(...))" the same as "values" of lines(values)?
>>>>
>>>> If yes,then why the range of lines(values) is different from
>>>> range(fitted(lm(...)))?
>>>
>>>You are plotting against the wrong x axis, and you don't see all the values.
>>>
>>>Duncan Murdoch
>>>
>>>> If no, what "values" refers to?
>>>>
>>>>
>>>>
>>>> At 2013-09-17 20:56:04,"Duncan Murdoch" <murdoch.duncan@gmail.com> wrote:
>>>>>On 13-09-17 8:06 AM, meng wrote:
>>>>>> Hi all:
>>>>>> I met a question about "lines".
>>>>>>
>>>>>>
>>>>>> attach(cars)
>>>>>>
>>>>>>
>>>>>> plot(dist ~ speed)
>>>>>> #add the regression line to the plot
>>>>>> lines(fitted(lm(dist~speed)) ~ speed)
>>>>>>
>>>>>>
>>>>>> plot(dist ~ speed)
>>>>>> #what kind of curve does the following command add to the plot?
>>>>>> lines(fitted(lm(dist~speed)))
>>>>>>
>>>>>>
>>>>>> My question is :
>>>>>> what kind of curve does the last command add to the plot?
>>>>>
>>>>>Look at the class of fitted(lm(...)).  It is "numeric".  So what you're
>>>>>seeing is the same as if you computed the fitted values, and then did
>>>>>
>>>>>lines(values)
>>>>>
>>>>>Since values is just a vector of numbers, that will plot them as y
>>>>>values against x values 1:length(values).  That's unlikely to be a
>>>>>useful thing to do.
>>>>>
>>>>>Duncan Murdoch
>>>>>
>>>>>>
>>>>>>
>>>>>> My guess:maybe the level of fitted values?
>>>>>>> range(fitted(lm(dist~speed)))
>>>>>> [1] -1.84946 80.73112
>>>>>>
>>>>>>
>>>>>> But from the plot,I can see the range of the curve is about 10 to 40 more or less,which is different from(-1.84946, 80.73112).So the curve must not be the fitted values.What kind of curve does the last command add to the plot then?
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> Many thanks for your help
>>>>>>
>>>>>>
>>>>>> My best
>>>>>> 	[[alternative HTML version deleted]]
>>>>>>
>>>>>> ______________________________________________
>>>>>> R-help@r-project.org mailing list
>>>>>> 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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