[R] Basic structure operations doubt

[Santosh Srinivas]

Thanks Josh. 

At your convenience, Any pointers on why this was designed like this? i.e. shouldn’t droplevels() be the default behavior?
I'm missing something in understanding on how these operations (manipulations) were designed to work.
 

-----Original Message-----
From: Joshua Wiley [mailto:jwiley.psych at gmail.com] 
Sent: 18 October 2010 07:47
To: Santosh Srinivas
Cc: r-help at r-project.org
Subject: Re: [R] Basic structure operations doubt

Hi,

The easiest way to get rid of the empty levels is with droplevels().
See ?droplevels for details.  It actually has a method for data frames
even.  So you could just do something like:

Indx_Constituents <- droplevels(Indx_Constituents)

or whatever your data frame was called and it will drop any unused
levels for you.

Cheers,

Josh

On Sun, Oct 17, 2010 at 7:06 PM, Santosh Srinivas
<santosh.srinivas at gmail.com> wrote:
> I'm doing these manipulations on the data frame and wondering why does R
> have to remember historical data on my operation and not just keep the
> needed info.
> Probably a basic fundamentals of the way R handles data .. Pls point me to
> the manual if possible ..
>
> I have this Index data:
>> head(NIFTY_INDX)
> �Constituents.list.of.S.P.CNX.Nifty � � � � � � � � � � � � �X � � � X.1
> X.2 � � � � �X.3
> 1
>
> 2 � � � � � � � � � � � Company Name � � � � � � � � � Industry � �Symbol
> Series � �ISIN Code
> 3
>
> 4 � � � � � � � � � � � � � ACC Ltd. CEMENT AND CEMENT PRODUCTS � � � ACC
> EQ INE012A01025
> 5 � � � � � � � �Ambuja Cements Ltd. CEMENT AND CEMENT PRODUCTS AMBUJACEM
> EQ INE079A01024
> 6 � � � � � � � � � � Axis Bank Ltd. � � � � � � � � � � �BANKS �AXISBANK
> EQ INE238A01026
>
>
> I Import the section that is relevant to me:
>
>> Indx_Constituents <- NIFTY_INDX[4:NROW(NIFTY_INDX),]
>> head(Indx_Constituents)
> �Constituents.list.of.S.P.CNX.Nifty � � � � � � � � � � � � � � �X
> X.1 X.2 � � � � �X.3
> 4 � � � � � � � � � � � � � ACC Ltd. � � CEMENT AND CEMENT PRODUCTS
> ACC �EQ INE012A01025
> 5 � � � � � � � �Ambuja Cements Ltd. � � CEMENT AND CEMENT PRODUCTS
> AMBUJACEM �EQ INE079A01024
> 6 � � � � � � � � � � Axis Bank Ltd. � � � � � � � � � � � � �BANKS
> AXISBANK �EQ INE238A01026
> 7 � � � � � � � � � �Bajaj Auto Ltd. AUTOMOBILES - 2 AND 3 WHEELERS
> BAJAJ-AUTO �EQ INE917I01010
> 8 � � �Bharat Heavy Electricals Ltd. � � � � � ELECTRICAL EQUIPMENT
> BHEL �EQ INE257A01018
> 9 �Bharat Petroleum Corporation Ltd. � � � � � � � � � � REFINERIES
> BPCL �EQ INE029A01011
>
>
>> colNames <- NIFTY_INDX[2,]
>> colNames
> �Constituents.list.of.S.P.CNX.Nifty � � � �X � �X.1 � �X.2 � � � X.3
> 2 � � � � � � � � � � � Company Name Industry Symbol Series ISIN Code
>
>
> I want to assign the info from colNames[1,] to Indx_Constituents .... I am
> unable to do this directly ... I can probably pull out the values and do it
> but there should be an easier way
>
>
> Now when I do this:
>> colNames[1,1]
> [1] Company Name
> 52 Levels: �ACC Ltd. Ambuja Cements Ltd. Axis Bank Ltd. Bajaj Auto Ltd.
> Bharat Heavy Electricals Ltd. Bharat Petroleum Corporation Ltd. Bharti
> Airtel Ltd. Cairn India Ltd. Cipla Ltd. Company Name ... Wipro Ltd.
>
> Why does R have to remember the 52 levels?? Why can't it just have the
> relevant data stored
> What are the alternatives so that I can simply have my needed data in my
> data frames?
>
> Thanks for your explanation.
>
>
> ----------------------------------------------------------------------------
> --------------------------
> Thanks R-Helpers. Yes, this is a silly question and it will not be repeated!
> :-)
>
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>



-- 
Joshua Wiley
Ph.D. Student, Health Psychology
University of California, Los Angeles
http://www.joshuawiley.com/