Hi:
When I call str() on an mlogit object, I seem to get warnings. This
code is from an example provided in the mlogit documentation:
library(mlogit)
data("Train", package="mlogit")
tr<-mlogit.data(Train, shape="wide", choice="choice",
varying=4:11,
sep="", alt.levels=c(1,2), id="id")
ml.train<-mlogit(choice~price+time+change+comfort| -1, tr)
str(ml.train)
List of 12
$ coefficients : atomic [1:4] -0.00148 -0.02868 -0.32634 -0.94573
..- attr(*, "fixed")= Named logi [1:4] FALSE FALSE FALSE FALSE
.. ..- attr(*, "names")= chr [1:4] "price"
"time" "change" "comfort"
$ logLik :Class 'logLik' : -1724 (df=4)
$ gradient : Named num [1:4] -3.94e-09 -1.40e-11 6.15e-13 -6.11e-13
..- attr(*, "names")= chr [1:4] "price" "time"
"change" "comfort"
$ gradi : num [1:2929, 1:4] -136 -281 -309 -139 448 ...
..- attr(*, "dimnames")=List of 2
.. ..$ : chr [1:2929] "1.1" "2.1" "3.1"
"4.1" ...
.. ..$ : chr [1:4] "price" "time" "change"
"comfort"
$ hessian : num [1:4, 1:4] -2.75e+08 2.48e+06 5.10e+04 9.95e+04
2.48e+06 ...
..- attr(*, "dimnames")=List of 2
.. ..$ : chr [1:4] "price" "time" "change"
"comfort"
.. ..$ : chr [1:4] "price" "time" "change"
"comfort"
$ est.stat :List of 5
..$ elaps.time:Class 'proc_time' Named num [1:5] 0.12 0 0.12 0 0
.. .. ..- attr(*, "names")= chr [1:5] "user.self"
"sys.self"
"elapsed" "user.child" ...
..$ nb.iter : num 5
..$ eps : num [1, 1] 0.00014
..$ method : chr "nr"
..$ code : num 2
..- attr(*, "class")= chr "est.stat"
$ fitted.values: num [1:2929, 1:2] 0.915 0.649 0.807 0.174 0.56 ...
..- attr(*, "dimnames")=List of 2
.. ..$ : NULL
.. ..$ : chr [1:2] "X1" "X2"
$ residuals : num [1:2929, 1:2] 0.0851 0.3512 0.1932 -0.1737 -0.5602 ...
..- attr(*, "dimnames")=List of 2
.. ..$ : chr [1:2929] "1.1" "2.1" "3.1"
"4.1" ...
.. ..$ : chr [1:2] "X1" "X2"
$ model :Classes ?mlogit.data? and 'data.frame': 5858 obs. of
5 variables:
..$ choice : logi [1:5858] TRUE FALSE TRUE FALSE TRUE FALSE ...
..$ price : int [1:5858] 2400 4000 2400 3200 2400 4000 4000 3200
2400 3200 ...
..$ time : int [1:5858] 150 150 150 130 115 115 130 150 150 150 ...
..$ change : int [1:5858] 0 0 0 0 0 0 0 0 0 0 ...
..$ comfort: int [1:5858] 1 1 1 1 1 0 1 0 1 0 ...
..- attr(*, "terms")=Classes 'terms', 'formula'
length 3 choice ~
price + time + change + comfort + -1
.. .. ..- attr(*, "variables")= language list(choice, price, time,
change, comfort)
.. .. ..- attr(*, "factors")= int [1:5, 1:4] 0 1 0 0 0 0 0 1 0 0 ...
.. .. .. ..- attr(*, "dimnames")=List of 2
.. .. .. .. ..$ : chr [1:5] "choice" "price"
"time" "change" ...
.. .. .. .. ..$ : chr [1:4] "price" "time"
"change" "comfort"
.. .. ..- attr(*, "term.labels")= chr [1:4] "price"
"time" "change" "comfort"
.. .. ..- attr(*, "order")= int [1:4] 1 1 1 1
.. .. ..- attr(*, "intercept")= int 0
.. .. ..- attr(*, "response")= int 1
.. .. ..- attr(*, ".Environment")=<environment: 0x187ef68>
.. .. ..- attr(*, "predvars")= language list(choice, price, time,
change, comfort)
.. .. ..- attr(*, "dataClasses")= Named chr [1:5]
"logical"
"numeric" "numeric" "numeric" ...
.. .. .. ..- attr(*, "names")= chr [1:5] "choice"
"price" "time" "change" ...
..- attr(*, "index")='data.frame': 5858 obs. of 3
variables:
.. ..$ chid: Factor w/ 2929 levels
"1","2","3","4",..: 1 1 2 2 3 3 4 4 5 5
...
.. ..$ alt : Factor w/ 2 levels "1","2": 1 2 1 2 1 2 1 2 1
2 ...
.. ..$ id : Factor w/ 235 levels
"1","2","3","4",..: 1 1 1 1 1 1 1 1 1 1
...
$ freq : 'table' int [1:2(1d)] 1474 1455
..- attr(*, "dimnames")=List of 1
.. ..$ : chr [1:2] "1" "2"
$ formula :Classes 'mFormula', 'Formula',
'formula' length 3
choice ~ price + time + change + comfort | -1
.. ..- attr(*, ".Environment")=<environment: R_GlobalEnv>
.. ..- attr(*, "lhs")=List of 1
.. .. ..$ : symbol choice
.. ..- attr(*, "rhs")=List of 2
.. .. ..$ : language price + time + change + comfort
.. .. ..$ : language -1
$ call : language mlogit(formula = choice ~ price + time +
change + comfort | -1, data = tr, method = "nr", print.level = 0)
- attr(*, "class")= chr "mlogit"
Warning messages:
1: In if (is.na(le)) " __no length(.)__ " else if (give.length) { :
the condition has length > 1 and only the first element will be used
2: In if (le > 0) P0("[1:", paste(le), "]") else
"(0)" :
the condition has length > 1 and only the first element will be used
I am surprised that I'm getting warnings. Am I doing something wrong
here, or is the mlogit object misformed in some way, or is there a
problem with str()?
I don't think the str() is specific to mlogit, since if I do
utils:::str.default(ml.train)
I get the same warnings.
Thanks.
Jen
sessionInfo()
R version 2.14.0 (2011-10-31)
Platform: x86_64-unknown-linux-gnu (64-bit)
locale:
[1] LC_CTYPE=en_US.UTF-8 LC_NUMERIC=C
[3] LC_TIME=en_US.UTF-8 LC_COLLATE=en_US.UTF-8
[5] LC_MONETARY=en_US.UTF-8 LC_MESSAGES=en_US.UTF-8
[7] LC_PAPER=C LC_NAME=C
[9] LC_ADDRESS=C LC_TELEPHONE=C
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C
attached base packages:
[1] stats graphics grDevices utils datasets methods base
other attached packages:
[1] mlogit_0.2-1 maxLik_1.0-2 miscTools_0.6-10 lmtest_0.9-29
[5] zoo_1.7-5 statmod_1.4.13 Formula_1.0-1
loaded via a namespace (and not attached):
[1] grid_2.14.0 lattice_0.20-0 sandwich_2.2-8 tools_2.14.0
