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Ray DiGiacomo, Jr.

2012-Dec-08 23:00 UTC

[R] Mean-Centering Question

Hello,

I'm trying to create a custom function that "mean-centers" data
and can be
applied across many columns.

Here is an example dataset, which is similar to my dataset:

*Location,TimePeriod,Units,AveragePrice*
Los Angeles,5/1/11,61,5.42
Los Angeles,5/8/11,49,4.69
Los Angeles,5/15/11,40,5.05
New York,5/1/11,259,6.4
New York,5/8/11,187,5.3
New York,5/15/11,177,5.7
Paris,5/1/11,672,6.26
Paris,5/8/11,514,5.3
Paris,5/15/11,455,5.2

I want to mean-center the "Units" and "AveragePrice"
Columns.

So, I created this function:

specialFunction <- function(x){ log(x) - colMeans(log(x), na.rm = T) }

If I use only "one" column in the first argument of the "by"
function,
everything is in fine.  For example the following code will work fine:

by(data[c("Units")],
data["Location"],
specialFunction)

But the following code will "not" work, because I have "two"
columns in the
first argument...

by(data[c("Units", "AveragePrice")],
data["Location"],
specialFunction)

Does anyone have any ideas as to what I am doing wrong?

Please note that I'm trying to get the following results (for the "Los
Angeles" group):

Los Angeles "Units" variable (Mean-Centered)
0.213682659
-0.005370907
-0.208311751

Los Angeles "AveragePrice" variable (Mean-Centered)
0.071790268
-0.072872965
0.001082696

Best Regards,

Ray DiGiacomo, Jr.
Healthcare Predictive Analytics Specialist
President, Lion Data Systems LLC
President, The Orange County R User Group
Board Member, TDWI
rayd@liondatasystems.com
(m) 408-425-7851
San Juan Capistrano, California USA
twitter.com/liondatasystems
linkedin.com/in/raydigiacomojr
youtube.com/user/liondatasystems/videos

	[[alternative HTML version deleted]]

Ray DiGiacomo, Jr.

2012-Dec-08 23:54 UTC

head link

[R] Mean-Centering Question

Hello,

I'm trying to create a custom function that "mean-centers" data
and can be
applied across many columns.

Here is an example dataset, which is similar to my dataset:

*Location,TimePeriod,Units,AveragePrice*
Los Angeles,5/1/11,61,5.42
Los Angeles,5/8/11,49,4.69
Los Angeles,5/15/11,40,5.05
New York,5/1/11,259,6.4
New York,5/8/11,187,5.3
New York,5/15/11,177,5.7
Paris,5/1/11,672,6.26
Paris,5/8/11,514,5.3
Paris,5/15/11,455,5.2

I want to mean-center the "Units" and "AveragePrice"
Columns.

So, I created this function:

specialFunction <- function(x){ log(x) - colMeans(log(x), na.rm = T) }

If I use only "one" column in the first argument of the "by"
function,
everything is in fine.  For example the following code will work fine:

by(data[c("Units")],
data["Location"],
 specialFunction)

But the following code will "not" work, because I have "two"
columns in the
first argument...

by(data[c("Units", "AveragePrice")],
data["Location"],
 specialFunction)

Does anyone have any ideas as to what I am doing wrong?

Please note that I'm trying to get the following results (for the "Los
Angeles" group):

Los Angeles "Units" variable (Mean-Centered)
0.213682659
-0.005370907
-0.208311751

Los Angeles "AveragePrice" variable (Mean-Centered)
0.071790268
-0.072872965
0.001082696

Best Regards,

Ray DiGiacomo, Jr.
Healthcare Predictive Analytics Specialist
President, Lion Data Systems LLC
President, The Orange County R User Group
Board Member, TDWI
rayd@liondatasystems.com
(m) 408-425-7851
San Juan Capistrano, California USA
twitter.com/liondatasystems
linkedin.com/in/raydigiacomojr
youtube.com/user/liondatasystems/videos

	[[alternative HTML version deleted]]

David Winsemius

2012-Dec-09 03:12 UTC

head link

[R] Mean-Centering Question

On Dec 8, 2012, at 3:54 PM, Ray DiGiacomo, Jr. wrote:
> Hello,
>
> I'm trying to create a custom function that "mean-centers"
data and
> can be
> applied across many columns.
>
> Here is an example dataset, which is similar to my dataset:
>
>dat <- read.table(text="Location,TimePeriod,Units,AveragePrice
Los Angeles,5/1/11,61,5.42
Los Angeles,5/8/11,49,4.69
Los Angeles,5/15/11,40,5.05
New York,5/1/11,259,6.4
New York,5/8/11,187,5.3
New York,5/15/11,177,5.7
Paris,5/1/11,672,6.26
Paris,5/8/11,514,5.3
Paris,5/15/11,455,5.2", header=TRUE,
sep=",")>
> I want to mean-center the "Units" and "AveragePrice"
Columns.
>
> So, I created this function:
>
> specialFunction <- function(x){ log(x) - colMeans(log(x), na.rm = T) }
I needed to modify this to avoid errors relating to how colMeans is  
expecting its arguments:

specialFunction2 <- function(x){ log(x) - mean(log(x), na.rm = T) }

aggregate(dat[3:4], dat[1], FUN=specialFunction2)

      Location    Units.1    Units.2    Units.3 AveragePrice.1  
AveragePrice.2
1 Los Angeles  0.2136827 -0.0053709 -0.2083118      0.0717903      
-0.0728730
2    New York  0.2354659 -0.0902535 -0.1452124      0.1014743      
-0.0871168
3       Paris  0.2193320 -0.0487031 -0.1706289      0.1173316      
-0.0491417
   AveragePrice.3
1      0.0010827
2     -0.0143575
3     -0.0681899
>
> If I use only "one" column in the first argument of the
"by" function,
> everything is in fine.  For example the following code will work fine:
>
> by(data[c("Units")],
> data["Location"],
> specialFunction)
>
> But the following code will "not" work, because I have
"two" columns
> in the
> first argument...
>
> by(data[c("Units", "AveragePrice")],
> data["Location"],
> specialFunction)
OK. So then I tried this with your function and was surprised to see  
that it also works:

 > by(dat[c("Units", "AveragePrice")],
+ dat["Location"],
+ specialFunction)
Location: Los Angeles
      Units AveragePrice
1  0.21368    0.0717903
2  2.27351   -2.3517586
3 -0.20831    0.0010827
------------------------------------------------------------------
Location: New York
      Units AveragePrice
4  0.23547     0.101474
5  3.47628    -3.653655
6 -0.14521    -0.014357
------------------------------------------------------------------
Location: Paris
      Units AveragePrice
7  0.21933      0.11733
8  4.52537     -4.62322
9 -0.17063     -0.06819
>
> Does anyone have any ideas as to what I am doing wrong?
I guess I don't. Cannot reproduce and my other methods worked as  
well.This also works with your version and with mine but I get the  
deprecation message for `mean.data.frame` from mine:

 > lapply( split(dat[3:4], dat[1]) , FUN=specialFunction )
$`Los Angeles`
      Units AveragePrice
1  0.21368    0.0717903
2  2.27351   -2.3517586
3 -0.20831    0.0010827

$`New York`
      Units AveragePrice
4  0.23547     0.101474
5  3.47628    -3.653655
6 -0.14521    -0.014357

$Paris
      Units AveragePrice
7  0.21933      0.11733
8  4.52537     -4.62322
9 -0.17063     -0.06819
>
> Please note that I'm trying to get the following results (for the
"Los
> Angeles" group):
>
> Los Angeles "Units" variable (Mean-Centered)
> 0.213682659
> -0.005370907
> -0.208311751
>
> Los Angeles "AveragePrice" variable (Mean-Centered)
> 0.071790268
> -0.072872965
> 0.001082696
-- 

David Winsemius, MD
Alameda, CA, USA

arun

2012-Dec-09 03:58 UTC

head link

[R] Mean-Centering Question

Hi,

It works for me also:
?by(dat1[c("Units","AveragePrice")],dat1[,1],specialFunction)
#dat1[, 1]: Los Angeles
?# ???? Units AveragePrice
#1? 0.2136827? 0.071790268
#2? 2.2735148 -2.351758623
#3 -0.2083118? 0.001082696
----------------------------------------------
#or

?by(cbind(Units=dat1[,3],AveragePrice=dat1[,4]),dat1[,1],specialFunction)
#INDICES: Los Angeles
?# ???? Units AveragePrice
#1? 0.2136827? 0.071790268
#2? 2.2735148 -2.351758623
#3 -0.2083118? 0.001082696
--------------------------------------------

A.K.






----- Original Message -----
From: "Ray DiGiacomo, Jr." <rayd at liondatasystems.com>
To: R Help <r-help at r-project.org>
Cc: 
Sent: Saturday, December 8, 2012 6:54 PM
Subject: [R] Mean-Centering Question

Hello,

I'm trying to create a custom function that "mean-centers" data
and can be
applied across many columns.

Here is an example dataset, which is similar to my dataset:

*Location,TimePeriod,Units,AveragePrice*
Los Angeles,5/1/11,61,5.42
Los Angeles,5/8/11,49,4.69
Los Angeles,5/15/11,40,5.05
New York,5/1/11,259,6.4
New York,5/8/11,187,5.3
New York,5/15/11,177,5.7
Paris,5/1/11,672,6.26
Paris,5/8/11,514,5.3
Paris,5/15/11,455,5.2

I want to mean-center the "Units" and "AveragePrice"
Columns.

So, I created this function:

specialFunction <- function(x){ log(x) - colMeans(log(x), na.rm = T) }

If I use only "one" column in the first argument of the "by"
function,
everything is in fine.? For example the following code will work fine:

by(data[c("Units")],
data["Location"],
specialFunction)

But the following code will "not" work, because I have "two"
columns in the
first argument...

by(data[c("Units", "AveragePrice")],
data["Location"],
specialFunction)

Does anyone have any ideas as to what I am doing wrong?

Please note that I'm trying to get the following results (for the "Los
Angeles" group):

Los Angeles "Units" variable (Mean-Centered)
0.213682659
-0.005370907
-0.208311751

Los Angeles "AveragePrice" variable (Mean-Centered)
0.071790268
-0.072872965
0.001082696

Best Regards,

Ray DiGiacomo, Jr.
Healthcare Predictive Analytics Specialist
President, Lion Data Systems LLC
President, The Orange County R User Group
Board Member, TDWI
rayd at liondatasystems.com
(m) 408-425-7851
San Juan Capistrano, California USA
twitter.com/liondatasystems
linkedin.com/in/raydigiacomojr
youtube.com/user/liondatasystems/videos

??? [[alternative HTML version deleted]]

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