From aragorn168b at gmail.com  Mon Aug  4 01:57:50 2014
From: aragorn168b at gmail.com (Arunkumar Srinivasan)
Date: Mon, 4 Aug 2014 01:57:50 +0200
Subject: [datatable-help] lapply without anonymous function
In-Reply-To: <CA+xi=qaDAJXEfhQo36m7Ot8Y0M8B9v3Df91QMcTcDtY=1+4evA@mail.gmail.com>
References: <CA+xi=qamZrLA2pv_MJLbqL1x2=3KV4uxwpdDBkvfFdFOR7jGNQ@mail.gmail.com>
 <CAP01uRn9qkmyaAJSEwOKRmOxEgrSJ1vhLiA1Uznqp0RxAwWdbA@mail.gmail.com>
 <CA+xi=qaDAJXEfhQo36m7Ot8Y0M8B9v3Df91QMcTcDtY=1+4evA@mail.gmail.com>
Message-ID: <etPan.53decc7e.3352255a.2ac0@Arunkumars-MacBook-Pro.local>

GSee and List,

With commit 1336, this now works:

require(data.table)
L = list(as.data.table(BOD), as.data.table(BOD))
lapply(L, "[", Time == 3L)
Please write back if you come across any issues.


Arun

From:?G See <gsee000 at gmail.com>
Reply:?G See <gsee000 at gmail.com>>
Date:?November 11, 2013 at 3:40:46 PM
To:?Gabor Grothendieck <ggrothendieck at gmail.com>>
Cc:?datatable-help at lists.r-forge.r-project.org <datatable-help at lists.r-forge.r-project.org>>
Subject:? Re: [datatable-help] lapply without anonymous function  

heh, after all my efforts to avoid subset(), it can be useful after all. :)  

Bug report filed, per Eduard's suggestion.  

On Mon, Nov 11, 2013 at 8:06 AM, Gabor Grothendieck  
<ggrothendieck at gmail.com> wrote:  
> On Sun, Nov 10, 2013 at 2:39 PM, G See <gsee000 at gmail.com> wrote:  
>> Hi,  
>>  
>> I have a list of data.tables and I am trying to extract a subset from  
>> each of them. I can achieve what I want with this:  
>>  
>>> L <- list(data.table(BOD), data.table(BOD))  
>>> lapply(L, function(x) x[Time==3L])  
>> [[1]]  
>> Time demand  
>> 1: 3 19  
>>  
>> [[2]]  
>> Time demand  
>> 1: 3 19  
>>  
>> However, I'd rather not type have to create an anonymous function. I  
>> tried the below, but `[.data.frame` is being dispatched.  
>>  
>>> lapply(L, "[", Time==3L)  
>> Error in `[.data.frame`(x, i) : object 'Time' not found  
>>  
>> Even if I am explicit, `[.data.table` does not get dispatched:  
>>  
>>> lapply(L, data.table:::`[.data.table`, Time==3L)  
>> Error in `[.data.frame`(x, i) : object 'Time' not found  
>>  
>> I'm guessing this is due to where evaluation takes place. Is there an  
>> alternate syntax I should use?  
>>  
>  
> subset works:  
>  
>> lapply(L, subset, Time == 3L)  
> [[1]]  
> Time demand  
> 1: 3 19  
>  
> [[2]]  
> Time demand  
> 1: 3 19  
>  
>  
>  
> --  
> Statistics & Software Consulting  
> GKX Group, GKX Associates Inc.  
> tel: 1-877-GKX-GROUP  
> email: ggrothendieck at gmail.com  
_______________________________________________  
datatable-help mailing list  
datatable-help at lists.r-forge.r-project.org  
https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/datatable-help  
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From thomas.harrop at ird.fr  Mon Aug  4 13:40:20 2014
From: thomas.harrop at ird.fr (Tom Harrop)
Date: Mon, 04 Aug 2014 13:40:20 +0200
Subject: [datatable-help] Unexpected behaviour using fast grouping
Message-ID: <53DF7124.20904@ird.fr>

Hello,

I'm trying to group a data.table that has duplicate keys, aggregating 
the values in another column by the value of the key.

There is a question and answer on the same topic on StackOverflow 
(http://stackoverflow.com/a/17033371/3017012), but when I follow the 
accepted answer I get different results:

 > library(data.table)
data.table 1.9.2  For help type: help("data.table")
 > dt = data.table(user_id = c(1,2,2,3), advertiser_id = c(1:4))
 > dt[,list(list(advertiser_id)), by = user_id]
    user_id  V1
1:       1 4,3
2:       2 4,3
3:       3 4,3

Where I expect:

    user_id  V1
1:       1   1
2:       2 2,3
3:       3   4

I can get the expected results (as above) using:

 > dt[,paste(advertiser_id, collapse = ","), by = user_id]

Have I missed something? I'm on R 3.1.1 in case the behaviour has 
changed recently.

Many thanks,

Tom

From aragorn168b at gmail.com  Mon Aug  4 13:44:22 2014
From: aragorn168b at gmail.com (Arunkumar Srinivasan)
Date: Mon, 4 Aug 2014 13:44:22 +0200
Subject: [datatable-help] Unexpected behaviour using fast grouping
In-Reply-To: <53DF7124.20904@ird.fr>
References: <53DF7124.20904@ird.fr>
Message-ID: <etPan.53df7216.519b500d.2ac0@Arunkumars-MacBook-Pro.local>

Hi Tom,
It has been fixed in 1.9.3, bug#481. You can scroll down the project page on instructions for installation..

Best,


Arun

From:?Tom Harrop <thomas.harrop at ird.fr>
Reply:?Tom Harrop <thomas.harrop at ird.fr>>
Date:?August 4, 2014 at 1:40:32 PM
To:?datatable-help at lists.r-forge.r-project.org <datatable-help at lists.r-forge.r-project.org>>
Subject:? [datatable-help] Unexpected behaviour using fast grouping  

Hello,  

I'm trying to group a data.table that has duplicate keys, aggregating  
the values in another column by the value of the key.  

There is a question and answer on the same topic on StackOverflow  
(http://stackoverflow.com/a/17033371/3017012), but when I follow the  
accepted answer I get different results:  

> library(data.table)  
data.table 1.9.2 For help type: help("data.table")  
> dt = data.table(user_id = c(1,2,2,3), advertiser_id = c(1:4))  
> dt[,list(list(advertiser_id)), by = user_id]  
user_id V1  
1: 1 4,3  
2: 2 4,3  
3: 3 4,3  

Where I expect:  

user_id V1  
1: 1 1  
2: 2 2,3  
3: 3 4  

I can get the expected results (as above) using:  

> dt[,paste(advertiser_id, collapse = ","), by = user_id]  

Have I missed something? I'm on R 3.1.1 in case the behaviour has  
changed recently.  

Many thanks,  

Tom  
_______________________________________________  
datatable-help mailing list  
datatable-help at lists.r-forge.r-project.org  
https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/datatable-help  
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From iruckaE at mail2world.com  Wed Aug  6 20:38:42 2014
From: iruckaE at mail2world.com (iembry)
Date: Wed, 6 Aug 2014 11:38:42 -0700 (PDT)
Subject: [datatable-help] operations (+, -, /,
 *) on unequal-sized data.table - Question from Stack Overflow
Message-ID: <1407350322075-4695146.post@n4.nabble.com>

Hi everyone, I posted my original question (it has been simplified since
then) on Stack Overflow
(http://stackoverflow.com/questions/24940246/operations-on-unequal-sized-data-table)
on 24 July and I haven't received any answers yet; however, I have received
a few comments.

Will anyone here be willing to provide me with some assistance?

Thank you for your time and consideration.



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From alanpaulkwan at gmail.com  Tue Aug 19 22:03:17 2014
From: alanpaulkwan at gmail.com (Alan Kwan)
Date: Tue, 19 Aug 2014 16:03:17 -0400
Subject: [datatable-help] fread for bin file?
Message-ID: <CAGdUEuRD79g-0BP2za6ZZ+9PB9UCbwRrXkVjtXE6TqV21kkSgA@mail.gmail.com>

I hope this isn't a bone-headed question in either sense of what or how I
am asking, but would it be in principle possible to adapt fread to read
fixed record binary .bin files?

I guess this is more of a feature request, although it's a help request if
someone's figured it out already.

TAQ bin files would be a major usage case, for instance. These are 60 gig
files that are usually 30-33 characters * 600M rows long.

An example would be reading a fixed record length, so imagine something like

 bidsiz<-readBin(qin,what='integer',size=4,n=1,endian='little')
  ofrsiz<-readBin(qin,what='integer',size=4,n=1,endian='little')
  mode<-readBin(qin,what='integer',size=2,n=1,endian='little')
  ex<-readBin(qin,  what='character',size=1,n=1,endian='little')

- Alan
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From michael.gahan at gmail.com  Thu Aug 21 15:42:20 2014
From: michael.gahan at gmail.com (Mike.Gahan)
Date: Thu, 21 Aug 2014 06:42:20 -0700 (PDT)
Subject: [datatable-help] Extracting specific values from a matrix
In-Reply-To: <1408582386386-4695768.post@n4.nabble.com>
References: <1408582386386-4695768.post@n4.nabble.com>
Message-ID: <1408628540569-4695793.post@n4.nabble.com>

Here is one way to approach this problem (there are lots of ways)

#Convert to model matrix to account for factor variables
iris <- model.matrix(~.-1,data=iris)

#Convert to data.table
iris <- data.table(iris)
candidates <- names(iris)

#Setup interaction variables for every combination
all.interactions <- as.data.table(t(combn(candidates,2)))
all.interactions[ , interaction := paste(V1,V2,sep="__")]
all.interactions[ , multiplier := paste(V1,V2,sep="*")]

#Add interactions to data
for (x in 1:nrow(all.interactions))
  iris[ , paste0(all.interactions$interaction[x]) :=
eval(parse(text=all.interactions$multiplier[x]))]



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From michael.gahan at gmail.com  Thu Aug 21 19:19:06 2014
From: michael.gahan at gmail.com (Mike.Gahan)
Date: Thu, 21 Aug 2014 10:19:06 -0700 (PDT)
Subject: [datatable-help] Extracting specific values from a matrix
In-Reply-To: <1408582386386-4695768.post@n4.nabble.com>
References: <1408582386386-4695768.post@n4.nabble.com>
Message-ID: <1408641546668-4695818.post@n4.nabble.com>

This is one method that might work.

#Melt matrix and then convert to data.table object
yourmatrix <- melt(yourmatrix)[melt(upper.tri(yourmatrix))$value,]
names(yourmatrix) <- c("v1", "v2", "value")
yourmatrix <- data.table(yourmatrix)

#Setkeys and reference quickly
setkey(yourmatrix,v1,v2)
yourmatrix[J("B","C")]



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From alanpaulkwan at gmail.com  Thu Aug 21 21:49:11 2014
From: alanpaulkwan at gmail.com (Alan Kwan)
Date: Thu, 21 Aug 2014 15:49:11 -0400
Subject: [datatable-help] (1.9.2) data.table crash when assign N values to
	N<1 rows
Message-ID: <CAGdUEuSgpAPSzS9+cd_zFFFoYyJn4b8BeVYZQU-01KbsPje54Q@mail.gmail.com>

Despite a few minutes of Googling I am unsure of whether this has been
reported, but if it hasn't the following reliably crashes R "seg fault",
on, if it matters, my Linux box

sample=data.table(a=1:50,b='N')
sample[50,b:=c(1,2,3)]

I don't know the guts of data.table to know whether it'd be easy to error
check without sacrificing performance. At the very least maybe some helpful
output?
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From aragorn168b at gmail.com  Thu Aug 21 22:18:43 2014
From: aragorn168b at gmail.com (Arunkumar Srinivasan)
Date: Thu, 21 Aug 2014 22:18:43 +0200
Subject: [datatable-help] (1.9.2) data.table crash when assign N values
 to N<1 rows
In-Reply-To: <CAGdUEuSgpAPSzS9+cd_zFFFoYyJn4b8BeVYZQU-01KbsPje54Q@mail.gmail.com>
References: <CAGdUEuSgpAPSzS9+cd_zFFFoYyJn4b8BeVYZQU-01KbsPje54Q@mail.gmail.com>
Message-ID: <etPan.53f65423.3b0fd379.14dda@Arunkumars-MacBook-Pro.local>

Hi Alan,

Could you please try it on 1.9.3:?https://github.com/Rdatatable/data.table?From what I vaguely recall, this has been fixed..

Arun

From:?Alan Kwan <alanpaulkwan at gmail.com>
Reply:?Alan Kwan <alanpaulkwan at gmail.com>>
Date:?August 21, 2014 at 9:49:44 PM
To:?datatable-help <datatable-help at lists.r-forge.r-project.org>>
Subject:? [datatable-help] (1.9.2) data.table crash when assign N values to N<1 rows  

Despite a few minutes of Googling I am unsure of whether this has been reported, but if it hasn't the following reliably crashes R "seg fault", on, if it matters, my Linux box

sample=data.table(a=1:50,b='N')
sample[50,b:=c(1,2,3)]

I don't know the guts of data.table to know whether it'd be easy to error check without sacrificing performance. At the very least maybe some helpful output?
_______________________________________________  
datatable-help mailing list  
datatable-help at lists.r-forge.r-project.org  
https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/datatable-help
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From fjbuch at gmail.com  Sat Aug 23 16:08:23 2014
From: fjbuch at gmail.com (Farrel Buchinsky)
Date: Sat, 23 Aug 2014 14:08:23 +0000 (UTC)
Subject: [datatable-help] I'd like to add you to my professional network on
	LinkedIn
Message-ID: <1679926256.10463241.1408802903712.JavaMail.app@ela4-app4978.prod>

Hi,

I&#39;d like to add you to my professional network on LinkedIn.

- Farrel

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