On 11/23/2011 09:38 PM, peter dalgaard wrote:

On Nov 23, 2011, at 10:03 , Jim Lemon wrote:

On 11/23/2011 06:47 AM, lucky7 wrote:
Hi,

I just start to use R today! I am reading the R Help on read.csv and the
description for header says "header is set to TRUE if and only if the first
row contains one fewer field than the number of columns". Why is that? My
data has the same number of fields in the first row as the number of
columns. I mean I have no problem opening my csv file I am just curious why
it should be one fewer.

Hi lucky7,
This looks like one of those little obscurities that sometimes appear in the help files. 
The default for read.csv is header=TRUE and I guess that the "...header is set to 
TRUE..." part means that if your file has one less field in the first line, header 
will be forced to TRUE as this is a part of the CSV specification. As Douglas Adams might 
have said,

"Don't panic."


Actually, no. It's a "little obscurity" alright, but the root cause is that the 
help file was originally written for read.table, with read.csv and friends as later 
bolt-ons. These actually call read.table internally, but if the header argument is 
missing to read.csv, the default (TRUE) will be passed to read.table. Thus, there is no 
way to induce the first-line-shorter logic. No big deal; nobody writes CSV files 
following that convention anyway.

Hmmm, my guess was wrong, but to quote Monty Python, "I do", or at least I struggled mightily with this leading delimiter business in the "delim.table" function. I do appreciate the expert correction, though.

The situation is in turn a niggle in the R language itself: missingness does 
not propagate.


Jim

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