[R] how to process multiple data files using R loop

[David Winsemius]

On Aug 8, 2014, at 11:25 AM, Fix Ace wrote:

> I have 16 files and would like to check the information of their first two lines, what I did: 
> 
> 
>> ls(pattern="P_")
>  [1] "P_3_utr_source_data"               "P_5_utr_source_data"              
>  [3] "P_exon_per_gene_cds_source_data"   "P_exon_per_gene_source_data"      
>  [5] "P_exon_source_data"                "P_first_exon_oncds_source_data"   
>  [7] "P_first_intron_oncds_source_data"  "P_first_intron_ongene_source_data"
>  [9] "P_firt_exon_ongene_source_data"    "P_gene_cds_source_data"           
> [11] "P_gene_source_data"                "P_intron_source_data"             
> [13] "P_last_exon_oncds_source_data"     "P_last_exon_ongene_source_data"   
> [15] "P_last_intron_oncds_source_data"   "P_last_intron_ongene_source_data" 
> 
> 

The results from `ls()` are not actual R names but rather are character vectors. To "promote" a character value to an R language-name you need the `get` function:

> 
>> for(i in ls(pattern="P_")){head(i, 2)}
> 

 for(i in ls(pattern="P_")){ head(get(i), 2)}  # Should work.

David.


> It obviously does not work since nothing came out
> 
> What I would like to see for the output is :
> 
>> head(P_3_utr_source_data,2)
>   V1
> 1  1
> 2  1
>> head(P_5_utr_source_data,2)
>   V1
> 1  1
> 2  1
>> 
> .
> 
> .
> .
> 
> 
> 
> Could anybody help me with this?
> 
> Thank you very much for your time:)
> 	[[alternative HTML version deleted]]
> 
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David Winsemius
Alameda, CA, USA