How to do indexing after splitting my data-frame?
'str' is your friend when trying to understand what the difference is:
x <- data.frame(a=1:10, b=sample(1:2, 10, TRUE)) x.s <- split(x, x$b) x.s
$`1`
a b
1 1 1
2 2 1
5 5 1
10 10 1
$`2`
a b
3 3 2
4 4 2
6 6 2
7 7 2
8 8 2
9 9 2
str(x.s['1'])
List of 1 $ 1:'data.frame': 4 obs. of 2 variables: ..$ a: int [1:4] 1 2 5 10 ..$ b: int [1:4] 1 1 1 1
str(x.s[['1']])
'data.frame': 4 obs. of 2 variables: $ a: int 1 2 5 10 $ b: int 1 1 1 1
x.s['1']$a
NULL
x.s[['1']]$a
[1] 1 2 5 10
Notice that x.s['1'] returns a 'list', while x.s[['1']] returns a dataframe which is probably what you were expecting. On Sat, Dec 20, 2008 at 4:10 PM, Oliver Bandel
<oliver at first.in-berlin.de> wrote:
Hello Jim, jim holtman <jholtman <at> gmail.com> writes:
try: myindex <- "01-Dec-2008" weblog_by_date[[myindex]]$host
[...] Ooops yes, that works! Thank you! I don't know why this works, and the other thing not. I thought the difference between [] and [[]] is just, that the one gives back a list and the other grabs out the values of a list by "unlist"ing it... so that one gets a vector instead of a complete list. Ciao, oliver
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Jim Holtman Cincinnati, OH +1 513 646 9390 What is the problem that you are trying to solve?