[R] How to take ID of number > 7.

[Rui Barradas]

Hello,


Berend Hasselman wrote
> 
> On 22-04-2012, at 13:03, Yellow wrote:
> 
>> I figured out something new that I would like to see if I can do this
>> more
>> easy with R then Excel. 
>> 
>> I have these huge files with data. 
>> For example: 
>> 
>> DataFile.csv 
>> ID Name log2 
>> 1 Fantasy 5.651 
>> 2 New 7.60518 
>> 3 Finding 8.9532 
>> 4 Looeka -0.248652 
>> 5 Vani 0.3548 
>> 
>> With like header1: ID, header 2: Name, header 3: log2 
>> 
>> Now I need to get the $ID out who have a &log2 value higher then 7. 
>> 
>> I know ho to grab the $log2 values with 7+ numbers. 
>> 
>> Log2HigherSeven = DataFile$log2 [ DataFile$log2 >= 7]  
>> 
> How about
> 
> DataFile[DataFile$log2 >= 7, c("ID","Log2")]
> 
> to get a dataframe with two columns ID and log2.
> 
> Berend
> 
> ______________________________________________
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> and provide commented, minimal, self-contained, reproducible code.
> 

Or maybe create an index vector into the rows of the data frame.
This would be more flexible, later any columns could be extracted.
The index can be a logical or integer vector.

inx.log <- DataFile$log2 >= 7
inx.int <- which(DataFile$log2 >= 7)

DataFile[inx.one.of.them, needed.cols]

As a side effect, it might also save some memory. Both indexes are
internally integers.

Hope this helps,

Rui Barradas


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