merge a list of data frames

Hi
-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
project.org] On Behalf Of Sam Steingold
Sent: Thursday, September 06, 2012 3:43 PM
To: David Winsemius
Cc: r-help at r-project.org
Subject: Re: [R] merge a list of data frames

* David Winsemius <qjvafrzvhf at pbzpnfg.arg> [2012-09-05 21:02:16 -
0700]:
On Sep 5, 2012, at 8:51 PM, Sam Steingold wrote:

I have a list of data frames:

str(data)
List of 4
$ :'data.frame':	700773 obs. of  3 variables:
 ..$ V1: chr [1:700773] "200130446465779" "200070050127778"
"200030633708779" "200010587002779" ...
 ..$ V2: int [1:700773] 0 0 0 0 0 0 0 0 0 0 ...
 ..$ V3: num [1:700773] 1 1 1 1 1 ...
$ :'data.frame':	700773 obs. of  3 variables:
 ..$ V1: chr [1:700773] "200130446465779" "200070050127778"
"200030633708779" "200010587002779" ...
 ..$ V2: int [1:700773] 0 0 0 0 0 0 0 0 0 0 ...
 ..$ V3: num [1:700773] 1 1 1 1 1 ...
$ :'data.frame':	700773 obs. of  3 variables:
 ..$ V1: chr [1:700773] "200130446465779" "200070050127778"
"200030633708779" "200010587002779" ...
 ..$ V2: int [1:700773] 0 0 0 0 0 0 0 0 0 0 ...
 ..$ V3: num [1:700773] 1 1 1 1 1 ...
$ :'data.frame':	700773 obs. of  3 variables:
 ..$ V1: chr [1:700773] "200160325893778" "200130647544079"
"200130446465779" "200120186959078" ...
 ..$ V2: int [1:700773] 0 0 0 0 0 0 0 0 0 0 ...
 ..$ V3: num [1:700773] 1 1 1 1 1 1 1 1 1 1 ...

I want to merge them.
Why? What are you expecting?
these are the results of applying a model to the test data.
the first column is the ID
the second column is the actual value
the third column is the model score

after I will merge the frames, I will
1. check that all the V2 columns are identical and drop all but one (I
guess I could just merge on c("V1","V2") instead, right?)
colSums(apply(do.call(cbind,lapply(data, "[", "V2")),1,diff)!=0)

shall give you 0 if there is no difference
2. compute the sum (or the mean, whatever is easier) of all the V3
columns
sapply(lapply(data, "[", "V3"), sum)
sapply(lapply(data, "[", "V3"), mean)

shall give you table of means or sums. Sorting them is straightforward

The most tedious part of my response was to prepare toy data. So please, maybe you shall be kind to us to provide them by an appropriate way

dput(header(data))

Regards
Petr
3. sort by the sum/mean of the V3 columns and evaluate the combined
model using the lift quality metric
(http://dl.acm.org/citation.cfm?id=380995.381018)

I have many more score files (not just 4), so it is not practical for
me to rename the column to something unique.

--
Sam Steingold (http://sds.podval.org/) on Ubuntu 12.04 (precise) X
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merge a list of data frames

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