I'm also going to guess that maybe your object
rainfall_by_site
has already been split into separate data frames (because of its name).
But by() does the splitting internally, so you should be passing it the
original unsplit data frame.
You could supply example data by providing the first few rows of each of the
first few groups. That would be enough to test with.
-Don
--
Don MacQueen
Lawrence Livermore National Laboratory
7000 East Ave., L-627
Livermore, CA 94550
925-423-1062
Lab cell 925-724-7509
On 9/17/18, 11:54 AM, "R-help on behalf of Rich Shepard"
<r-help-boun...@r-project.org on behalf of rshep...@appl-ecosys.com> wrote:
My dataframe has 113K rows split by a factor into 58 separate
data.frames,
with a different numbers of rows (see error output below).
I cannot think of a way of proving a sample of data; if a sample for a
MWE
is desired advice on produing one using dput() is needed.
To summarize each group within this dataframe I'm using by() and getting
an error because of the different number of rows:
> by(rainfall_by_site, rainfall_by_site[, 'name'], function(x) {
+ mean.rain <- mean(rainfall_by_site[, 'prcp'])
+ })
Error in (function (..., row.names = NULL, check.rows = FALSE, check.names
= TRUE, :
arguments imply differing number of rows: 4900, 1085, 1894, 2844, 3520,
647, 239, 3652, 3701, 3063, 176, 4713, 4887, 119, 165, 1221, 3358, 1457,
4896, 166, 690, 1110, 212, 1727, 227, 236, 1175, 1485, 186, 769, 139, 203,
2727, 4357, 1035, 1329, 1454, 973, 4536, 208, 350, 125, 3437, 731, 4894,
2598, 2419, 752, 427, 136, 685, 4849, 914, 171
My web searches have not found anything relevant; perhaps my search terms
(such as 'R: apply by() with different factor row numbers') can be improved.
The help pages found using apropos('by') appear the same: ?by,
?by.data.frame, ?by.default and provide no hint on how to work with unequal
rows per factor.
How can I apply by() on these data.frames?
Rich
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