[R] dropping rows

Tobias Muhlhofer t.muhlhofer at lse.ac.uk
Thu Dec 2 01:57:47 CET 2004


The problem is that there is extremely little on dataframes or matrices 
in "An Intro to R", which I did read and I frankly don't know where else 
to go.

Once I know a function like subset() exists, I can then read the help 
files on it and that's fine, but I would never dream this function up 

As for indexing, I DID read "An Introduction to R" and I did NOT catch 
the part where it says you can use any variable in the dataframe to 
index it, nor would I have thought of it by myself. From that 
documentation, I only learned about using row-labels to index things...

But I am definitely thankful for the quick help given to me by people on 
this list, and so I guess being RTFM'ed is a small price to pay for 
figuring out how to solve the problem I need to solve.


Jeff Laake wrote:
> Here's an example:
> earlydata=data[data$year<1960,]
> Lookup help and read manuals on manipulating dataframes.
> Tobias Muhlhofer wrote:
>> Hi!
>> Sorry for asking a trivial questions, but I can't seem to figure this 
>> out.
>> I have a dataframe called master containing 30-odd variables.
>> In this dataframe, I have observations across these 30 variables from 
>> 1930 to 2003 (I've made a "year" variable). How can I drop all rows 
>> for which the year is less than 1960? I'm assuming something with 
>> ifelse() but I can't quite figure it out.
>> I would appreciate a suggestion of some syntax.
>> Thanks!
>>     Toby
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