You were clearly mistaken.
dataframe$column is almost the same as dataframe[["column"]], except that the $
does partial matching. Both of these "extract" a list element.
A data frame is a list where all elements are vectors of the same length. A
list is a vector where each element can refer to any of a variety of types of
objects. The names of the objects in the list are associated with the list
vector, not the referred objects (e.g. columns). The [] operator "slices" the
list but keeps the names and referring semantics. The [[]] extraction operator
(and its pal $) refer to a single element out of the list, losing access to the
containing list and the names that go with it.
The Introduction to R document has all this in it... it just usually glazes
your eyes the first few times you read it. You might find the R Inferno more
entertaining.
--
Sent from my phone. Please excuse my brevity.
On May 30, 2016 11:45:52 PM PDT, g.maub...@weinwolf.de wrote:
>Hi All,
>
>I thought dataset$variable is the same as dataset["variable"]. I tried
>the
>following:
>
>> str(ZWW_Kunden$Branche)
>chr [1:49673] "231" "151" "151" "231" "231" "111" "231" "111" "231"
>"231"
>"151" "111" ...
>> str(ZWW_Kunden["Branche"])
>'data.frame':49673 obs. of 1 variable:
> $ Branche: chr "231" "151" "151" "231" ...
>
>and get different results: "chr {1:49673]" vs. "data.frame". First one
>is
>a simple vector, second one is a data.frame.
>
>This has consequences when subsetting a dataset and filter cases:
>
>> ZWW_Kunden["Branche"] %in% c("315", "316", "317")
>[1] FALSE
>
>> head(ZWW_Kunden$Branche %in% c("315", "316", "317")) # head() only to
>
>shorten output
>[1] FALSE FALSE FALSE FALSE FALSE FALSE
>
>I have thought dataset$variable is the same as dataset["variable"] but
>actually it's not.
>
>Can you explain what the difference is?
>
>Kind regards
>
>Georg
>
>__
>R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
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>PLEASE do read the posting guide
>http://www.R-project.org/posting-guide.html
>and provide commented, minimal, self-contained, reproducible code.
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