[R] Problems plotting and regression w.r.t. date data type on x axis

[Kategoricus]

Hello,

probably a newbie question, but i didnt find any information on
plotting/regressing w.r.t. a date data type. My trials were unfruitful. Can
anyone help ? Thanks in advance!

Here is my interaction with R:


> tabelle
date number date2
1 2009-01-1 1673 2009-01-01
2 2009-12-1 2111 2009-12-01
3 2010-7-1 2487 2010-07-01
4 2013-2-1 4301 2013-02-01
> regression.punkte<-lm(tabelle$number ~ tabelle$date2)
Fehler in model.frame.default(formula = tabelle$number ~ tabelle$date2, :
ungültiger Typ (list) für die Variable 'tabelle$date2'
> regression.punkte<-lm(tabelle$number ~ tabelle$date)
> plot(tabelle$date2,tabelle$number, pch=19, xlab="date of retrieval",
> ylab="number of animals") ***R DRAWS THIS***
> regression.punkte

Call:
lm(formula = tabelle$number ~ tabelle$date)

Coefficients:
(Intercept) tabelle$date2009-12-1 tabelle$date2010-7-1
1673 438 814
tabelle$date2013-2-1
2628

> abline(regression.punkte, lwd=2) ***R DOES NOT DRAW LINE***
Warnmeldung:
In abline(regression.punkte, lwd = 2) :
nutze nur die ersten beiden von 4 Regressionskoeffizienten
> summary(regression.punkte)

Call:
lm(formula = tabelle$number ~ tabelle$date)

Residuals:
ALL 4 residuals are 0: no residual degrees of freedom!

Coefficients:
Estimate Std. Error t value Pr(>|t|)
(Intercept) 1673 NA NA NA
tabelle$date2009-12-1 438 NA NA NA
tabelle$date2010-7-1 814 NA NA NA
tabelle$date2013-2-1 2628 NA NA NA

Residual standard error: NaN on 0 degrees of freedom
Multiple R-squared: 1, Adjusted R-squared: NaN
F-statistic: NaN on 3 and 0 DF, p-value: NA



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