[R] Just another pattern matching / indexing question

[dunner]

Hi all, thank you for your patience.

I am dealing with a large dataset detailing patients and medications

Medications are hard to code, as they are (usually) meaningless unless
matched with doses.

I have a dataframe with vectors (Drug1, Drug2..... Drug 16) and individual
patients are represented by rows.
The vectors are actually factors, with 100s of possible levels (all the
drugs the patient could be on).

All I want to do is produce a vector of logicals (TTTTFFFFTTT......) that I
can cbind into the dataframe, that will tell me whether a patient is or is
not on a particular, important drug.

This i so I can use particularly important drugs' presence or absence as
categorical covariates in a model.

I've tried grep, to search along the rows, and I can generate a vector of
identifiers, but I cannot seem to generate the vector of logicals.

I realise I'm doing something simply wrong.


names(drugindex)
 [1] "book.MRN" "DRUG1"    "DRUG2"    "DRUG3"    "DRUG4"    "DRUG5"   
 [7] "DRUG6"    "DRUG7"    "DRUG8"    "DRUG9"    "DRUG10"   "DRUG11"  
[13] "DRUG12"   "DRUG13"   "DRUG14"   "DRUG15"   "DRUG16"  

> truvec<-drugindex$book.MRN[as.vector(unlist(apply(drugindex[,2:17], 2,
> grep, pattern="Lamotrigine")))]
> truvec
truvec
[1] 0024633  0008291  0008469  0030599  0027667 
37 Levels: 0008291  0008469  0010188  0014217  0014439  0015822  ... 0034262 

> head(drugindex)
   book.MRN       DRUG1        DRUG2          DRUG3        DRUG4       
DRUG5
4  0008291  Venlafaxine Procyclidine  Flunitrazepam Amisulpiride   
Clozapine
31 0008469  Venlafaxine  Mirtazapine        Lithium   Olanzapine  
Metoprolol
3  0010188   Flurazepam    Valproate     Olanzapine  Mirtazapine
Esomeprazole
13 0014217      Aspirin     Ramipril Zuclopenthixol    Lorazepam 
Haloperidol
15 0014439    Zopiclone     Diazepam    Haloperidol  Paracetamol        
<NA>
5  0015822   Olanzapine  Venlafaxine        Lithium  Haloperidol  
Alprazolam
         DRUG6      DRUG7      DRUG8      DRUG9          DRUG10 DRUG11
DRUG12
4  Lamotrigine Alprazolam    Lithium Alprazolam            <NA>   <NA>  
<NA>
31 Lamotrigine   Ramipril Alprazolam   Zolpidem Trifluoperazine   <NA>  
<NA>
3  Paracetamol Alprazolam Citalopram       <NA>            <NA>   <NA>  
<NA>
13        <NA>       <NA>       <NA>       <NA>            <NA>   <NA>  
<NA>
15        <NA>       <NA>       <NA>       <NA>            <NA>   <NA>  
<NA>
5         <NA>       <NA>       <NA>       <NA>            <NA>   <NA>  
<NA>
   DRUG13 DRUG14 DRUG15 DRUG16
4    <NA>   <NA>   <NA>   <NA>
31   <NA>   <NA>   <NA>   <NA>
3    <NA>   <NA>   <NA>   <NA>
13   <NA>   <NA>   <NA>   <NA>
15   <NA>   <NA>   <NA>   <NA>
5    <NA>   <NA>   <NA>   <NA>

And what I want is a vector of logicals for  each drug, saying whether that
patient is on it 

Thank you all for your time.

Ross Dunne MRCPsych






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