[R] conditional with and operators

[Christos Hatzis]

Mark,

It is not clear whether you are dealing with a single list or something more
complex, such as a list of lists or a list of data frames.  In the case of a
single list, you don't really need any of the 'apply' functions.  The main
problem in your code is the use of '&&' instead of '&':

> test.1 <- list(id = 1:50, tick = rnorm(50, 900, 50), tvis = sample(1:100,
50))
> test.1
$id
 [1]  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
25 26 27 28 29
[30] 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

$tick
 [1]  891.5450  997.4262  884.0224  892.8317  903.7194  862.7283  913.8126
895.6072
 [9]  923.2599  823.0804  828.0575  919.2257  879.8593  833.6082  924.6253
889.6797
[17]  880.2397 1022.9587  898.3806  953.0213  911.8132  932.3018  960.7257
905.0871
[25] 1018.8407  991.3910  931.3846  960.0569  793.5923  899.3268  921.0783
929.6885
[33]  940.9550  882.9791  914.9050  897.7252  970.7575  867.9848  901.2766
912.0851
[41]  856.8671  878.3230  906.9869  903.8044  882.1902  972.3030  923.9107
869.6903
[49]  836.6934  912.6101

$tvis
 [1] 67  8 89 36 91 30 63 38 22 44 18 79 48 90 82  6 81 39 69  7 45 86 32 43
99 23 34 54 37
[30]  1 15  5 14 87 77 27 93 94 71 60 83 62 92 72 26 80 58 98 84 78

> test.1$id > 10 & test.1$tick > 910
 [1] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE  TRUE
FALSE FALSE
[15]  TRUE FALSE FALSE  TRUE FALSE  TRUE  TRUE  TRUE  TRUE FALSE  TRUE  TRUE
TRUE  TRUE
[29] FALSE FALSE  TRUE  TRUE  TRUE FALSE  TRUE FALSE  TRUE FALSE FALSE  TRUE
FALSE FALSE
[43] FALSE FALSE FALSE  TRUE  TRUE FALSE FALSE  TRUE

> test.1$tvis[test.1$id > 10 & test.1$tick > 910]
 [1] 79 82 39  7 45 86 32 99 23 34 54 15  5 14 77 93 60 80 58 78 

If this is not what you have, it would be helpful to provide an example of
the data structure that you are dealing with, as the posting guide suggests.

-Christos

> -----Original Message-----
> From: r-help-bounces at r-project.org 
> [mailto:r-help-bounces at r-project.org] On Behalf Of Altaweel, Mark R.
> Sent: Tuesday, August 19, 2008 4:10 PM
> To: r-help at r-project.org
> Subject: [R] conditional with and operators
> 
> Hi,
> 
> I have a problem in which I am parsing data from a list.  I 
> am simply trying to return data that has several conditions 
> being true.  Here is my syntax below:
> 
> d<-sapply(res,function(.df){(.df$TimesVisited[.df$Tick>912 && 
> .df$Id>0])})   #res is the list, and I am trying to return a 
> result that has two true conditions (that is the variable 
> Tick should be greate than 912 and Id should be greater than 0
> 
> This returns an array of 10 with integer values of 0. This is 
> the incorrect result
> 
> However, if I do the same syntax except I remove the && 
> statement (i.e. the second conditional), then the result 
> producing something that makes sense, which is all values 
> that are Tick and greater than 912.
> 
> Can someone let me know how I can setup my data to be parsed 
> so I can have 2 or multiple conditionals in my function that 
> is looking at an array.
> 
> Thanks in advance.
> 
> Mark
> 
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> 
>