R help - Apr 2011 - syntax to subset for multiple values from a single variable

Hi All,
 
Is it possible to use the subset() function to select data based on multiple
values of a single variable from a data frame.
 
My actual data set is much bigger and would like to illustrate with
following dataset
> df = data.frame(x =
c('a','b','c','d','e','f','g','h','a','a','b','b'),
y
= 1:12)
I would like to select all rows where x = a or b. 
 
> subset(df, x == c('a','b')) # this command did not return
all rows where x
is equal to a or b

   x  y

1  a  1

2  b  2

9  a  9

12 b 12
 
> df[df$x %in% c('a','b'),] # subsetting using subscripts
returned all rows
   x  y

1  a  1

2  b  2

9  a  9

10 a 10

11 b 11

12 b 12
 
I know there might be a problem with subset syntax that I have used, but
could'nt figure out what it is. Any insights from members will be highly
appreciated and thanks for the same.
 
Regards,
 
S.N.V. Krishna

 

	[[alternative HTML version deleted]]

Hi,

I'm not sure what you're looking for because it looks to me that you 
have the answer already...
Is this what you want:
subset(df, x %in% c('a','b'))
?

Ivan

Le 4/6/2011 10:45, SNV Krishna a ?crit :
> Hi All,
>
> Is it possible to use the subset() function to select data based on
multiple
> values of a single variable from a data frame.
>
> My actual data set is much bigger and would like to illustrate with
> following dataset
>> df = data.frame(x =
c('a','b','c','d','e','f','g','h','a','a','b','b'),
y
> = 1:12)
> I would like to select all rows where x = a or b.
>
>
>> subset(df, x == c('a','b')) # this command did not
return all rows where x
> is equal to a or b
>
>     x  y
>
> 1  a  1
>
> 2  b  2
>
> 9  a  9
>
> 12 b 12
>
>> df[df$x %in% c('a','b'),] # subsetting using subscripts
returned all rows
>     x  y
>
> 1  a  1
>
> 2  b  2
>
> 9  a  9
>
> 10 a 10
>
> 11 b 11
>
> 12 b 12
>
> I know there might be a problem with subset syntax that I have used, but
> could'nt figure out what it is. Any insights from members will be
highly
> appreciated and thanks for the same.
>
> Regards,
>
> S.N.V. Krishna
>
>
>
> 	[[alternative HTML version deleted]]
>
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-- 
Ivan CALANDRA
PhD Student
University of Hamburg
Biozentrum Grindel und Zoologisches Museum
Abt. S?ugetiere
Martin-Luther-King-Platz 3
D-20146 Hamburg, GERMANY
+49(0)40 42838 6231
ivan.calandra at uni-hamburg.de

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