Hello,
No, flights[2] is *not* equal to flights$months. The former is a
data.frame with only one column, therefore it has a dimension attribute.
The latter is a column, a vector of the data.frame flights, it does not
have the attribute dim set.
The difference is very important, see what clas
Hi,
You might want to become familiar with the ?str and ?dim functions, which can
help you identify the structure of the objects that you are passing to
colMeans().
In the first case, flights[2] is a data frame with a single column, so will
have two dimensions with a row and column structure.
On 04/11/2020 8:26 a.m., Engin Yılmaz wrote:
Dear
I use *flights* database library(nycflights13)
The following code is working as
colMeans(flights[2])
* 6.54851*
but other code is not working as
colMeans(flights$month)
*Error in colMeans(flights$month) : *
* 'x' must be an array of at lea
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