[R] subset of obersevation depending on multiple conditions

[Ivan Calandra]

Hi Christoph,

I'm not sure I understand your conditions. It is an "AND" or an "OR", 
i.e. must both conditions be met to subset or any one of them?
 From your explanation, I would think you really mean AND, but then I 
don't understand why you would select both lines 3 and 4.

I would just say:
df[df$N <= 0.3, ]
but I might be missing something.

You should also be careful with floating point numbers, I guess.

HTH,
Ivan

--
Ivan Calandra
University of Franche-Comté
Laboratoire Chrono-Environnement
Bureau ATER -107L
16, Route de Gray
25030 Besançon Cedex, France
ivan.calandra at univ-fcomte.fr
+33 (0) 381 66 20 60
http://chrono-environnement.univ-fcomte.fr/spip.php?article1830

Le 28/04/14 10:37, Christoph Schlächter a écrit :
> Hello,
>
> I want to subset a data.frame containing the variables "Date" in (%Y %m %d
> ) and "N".
>
> I want to print "Date" and "N" if  N is less than or equal to 0.3 and if
> "N" is also less than or equal to 0.3 on the day before the day where "N"
> is less than or equal to 0.3.
>
> This would be the case in line 3 and 4 , 6 and 7, 12 to 18, and so on.
>
> "Date"    "N"
> "1"    2010-01-01    0
> "2"    2010-01-02    1.9
> "3"    2010-01-03    0
> "4"    2010-01-04    0
> "5"    2010-01-05    1.6
> "6"    2010-01-06    0
> "7"    2010-01-07    0.3
> "8"    2010-01-08    0
> "9"    2010-01-09    1.1
> "10"    2010-01-10    1.7
> "11"    2010-01-11    2.6
> "12"    2010-01-12    0
> "13"    2010-01-13    0
> "14"    2010-01-14    0
> "15"    2010-01-15    0
> "16"    2010-01-16    0
> "17"    2010-01-17    0
> "18"    2010-01-18    0.2
> "19"    2010-01-19    0
> "20"    2010-01-20    0
> "21"    2010-01-21    0
> "22"    2010-01-22    0
> "23"    2010-01-23    0
> "24"    2010-01-24    0
> "25"    2010-01-25    0
> "26"    2010-01-26    0
> "27"    2010-01-27    1.9
> "28"    2010-01-28    6.2
> "29"    2010-01-29    0
> "30"    2010-01-30    0
>
> I tried some methods with subset but I couldn't work it out. Maybe I have
> to use something like " for (i in x) {} but as a beginner I really don't
> know how to do it.
>
> Can somebody please help me with this.
>
> Thanks in advance,
>
> Christoph
>
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>
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