[R] Merging data frames on two conditions

[David Winsemius]

On Apr 6, 2010, at 4:03 PM, Abhishek Pratap wrote:

> Hi David
>
> Here it is. You can ignore the bio jargon if it sounds confusing.

Sometimes it is essential to have domain details.

> The corresponding data type of column (SNP, chr) on which I am  
> applying merge is same.
>
> merge(data_lane6_snps, data_lane6_snps_rsid , by = c("SNP,"chr"))
>
>
> str(data_lane6_snps)
> 'data.frame':   7724462 obs. of  10 variables:
>  $ chr           : Factor w/ 25 levels "chr1","chr10",..: 1 1 1 1 1  
> 1 1 1 1 1 ...
>  $ SNP           : int  100 101 103 108 179 180 191 197 218 222 ...
>  $ reference     : Factor w/ 5 levels "A","C","G","N",..: 2 2 5 2 2  
> 5 2 2 1 5 ...
>  $ genotype      : Factor w/ 10 levels "A","C","G","K",..: 1 1 1 8 2  
> 2 3 8 2 2 ...
>  $ consensus_qual: int  0 0 0 4 33 33 19 19 19 19 ...
>  $ snp_qual      : int  0 0 0 4 0 33 19 19 19 19 ...
>  $ rms_qual      : int  0 0 0 0 21 21 21 21 21 21 ...
>  $ depth         : int  1 1 1 1 2 2 2 2 2 2 ...
>  $ bases         : Factor w/ 453774 levels "^!,","^!,^!,",..: 5 5 5  
> 410998 49793 155731 284998 416878 133393 133393 ...
>  $ base_quality  : Factor w/ 555104 levels "`","``","```",..: 359  
> 359 359 54813 92856 92856 92856 92856 92539 55424 ...
>
> > str(data_lane6_snps_rsid)
> 'data.frame':   797807 obs. of  4 variables:
>  $ chr : Factor w/ 24 levels "1","10","11",..: 3 3 3 3 3 3 3 3 3 3 ...
>  $ SNP : int  68143872 11071026 69423434 12394791 1302846 95330693  
> 3921381 57122299 41899656 76990037 ...

Looking at this line and the line for "SNP" in the above dataframe I  
am not seeing that these are exhibiting much similarity in range.  
There are 10 times few observations. What was you plan for the non- 
matching cases? Did you really mean that you wanted a right outer join?

You might get information by trying:

length(intersect(data_lane6_snps$SNP, data_lane6_snps_rsid$SNP))

That would tell you how many potential matches you might have on the  
basis of SNP numbers, Although an SNP match might or might not be a  
full match given the chr matching that is also being specified.


>  $ end : int  68143872 11071026 69423434 12394791 1302846 95330693  
> 3921381 57122299 41899656 76990037 ...
>  $ rsid: Factor w/ 797807 levels "rs10","rs10000010",..: 100229  
> 685690 505395 470219 780326 29342 29263 327909 434159 723152 ...
>
>
> On Tue, Apr 6, 2010 at 3:59 PM, David Winsemius <dwinsemius at comcast.net 
> > wrote:
>
> On Apr 6, 2010, at 3:54 PM, Abhishek Pratap wrote:
>
> Hi Guys
>
> I have two data frames which I would like to merge on two conditions.
>
> I am doing the following  (abstract form)
>
> new.data.frame <- merge(df1,df2, by=c("Col1","Col2"))

So I am guessing that you really wanted just this:

new.data.frame <- merge(df1,df2)

?merge

Since the default for merge is:  by = intersect(names(x), names(y)),  
this would have been equivalent to

new.data.frame <- merge(df1,df2, by=c("chr", "SNP") )

See above regarding the possibility that you have non-congruent SNP  
labeling problems.



>
> What does
>
>  str(df1) ; str(df2)
>
> ... show?
>
>
>
> It is giving me a null result.
>
> Basically I need to apply two conditions.
>
> I also tried sqldf but it is running forever. Will indexing help ?
>
> temp <- sqldf("select  
> a.chr,a.SNP,a.snp_qual,a.rms_qual,a.depth,b.rsid FROM
> + data_lane6_snps a,
> + data_lane6_snps_rsid b
> + WHERE
> + a.SNP = b.SNP
> + AND
> + a.chr = b.chr
> + ")
>
> Thanks!
> -Abhi
>
>        [[alternative HTML version deleted]]
>
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> and provide commented, minimal, self-contained, reproducible code.
>
> David Winsemius, MD
> West Hartford, CT
>
>

David Winsemius, MD
West Hartford, CT