How should I format my data for the R mlogit package?
I am using the mlogit package with R.
After importing my data using:
t <-read.csv('junk.csv',header=TRUE, sep=",", dec=".")
and call:
x <- mlogit.data(t,choice="D",shape="long",id.var="key",alt.var="altkey")
I am getting the following error:
Error in `row.names<-.data.frame`(`*tmp*`, value = c("1.1", "1.2", "1.3", :
duplicate 'row.names' are not allowed
In addition: Warning message:
non-unique values when setting 'row.names': ‘1.1’, ‘1.2’, ‘1.3’, ‘1.4’, ‘1.5’, ‘1.6’
Any ideas how to fix it?
My data exist in the following format in a csv file:
[junk.csv]
key,altkey,A,B,C,D
201005131,1,2.6,118.17,117,0
201005131,2,1.4,117.11,115,0
201005131,3,1.1,117.38,122,1
201005131,4,24.6,,122,0
201005131,5,48.6,91.90,122,0
201005131,6,59.8,,122,0
201005132,1,20.2,118.23,113,0
201005132,2,2.5,123.67,120,1
201005132,3,7.4,116.30,120,0
201005132,4,2.8,118.86,120,0
201005132,5,6.9,124.72,120,0
201005132,6,2.5,123.81,120,0
201005132,7,8.5,119.23,115,
My experience of mlogit is that it isn't very forgiving about data that isn't exactly the way it should be.
In your case, I notice that the first respondent has 6 alternatives, while the second respondent has 7 alternatives. If you format your data to have an equal number of alternatives for each respondent the mlogit.data function works:
dat <- read.table(sep=",",text="
key,altkey,A,B,C,D
201005131,1, 2.6,118.17,117,0
201005131,2,1.4,117.11,115,0
201005131,3,1.1,117.38,122,1
201005131,4,24.6,,122,0
201005131,5,48.6,91.90,122,0
201005131,6,59.8,,122,0
201005132,1,20.2,118.23,113,0
201005132,2,2.5,123.67,120,1
201005132,3,7.4,116.30,120,0
201005132,4,2.8,118.86,120,0
201005132,5,6.9,124.72,120,0
201005132,6,2.5,123.81,120,0
201005132,7,8.5,119.23,115,0
", header=TRUE)
Running mlogit on all of the data reproduces the error:
> mlogit.data(dat, choice="D", shape="long", id.var="key", alt.var="altkey")
Error in `row.names<-.data.frame`(`*tmp*`, value = c("1.1", "1.2", "1.3", :
duplicate 'row.names' are not allowed
In addition: Warning message:
non-unique values when setting 'row.names': '1.1', '1.2', '1.3', '1.4', '1.5', '1.6'
However, removing line number 13, ie the 7th alternative, works:
> mlogit.data(dat[-13, ], choice="D", shape="long", id.var="key", alt.var="altkey")
key altkey A B C D
1.1 201005131 1 2.6 118.17 117 FALSE
1.2 201005131 2 1.4 117.11 115 FALSE
1.3 201005131 3 1.1 117.38 122 TRUE
1.4 201005131 4 24.6 NA 122 FALSE
1.5 201005131 5 48.6 91.90 122 FALSE
1.6 201005131 6 59.8 NA 122 FALSE
2.1 201005132 1 20.2 118.23 113 FALSE
2.2 201005132 2 2.5 123.67 120 TRUE
2.3 201005132 3 7.4 116.30 120 FALSE
2.4 201005132 4 2.8 118.86 120 FALSE
2.5 201005132 5 6.9 124.72 120 FALSE
2.6 201005132 6 2.5 123.81 120 FALSE
Of course, this isn't very satisfactory, since it destroys some of the data. A better solution is to construct the data in a format that mlogit() expects, and then call mlogit() directly:
dat$key <- factor(as.numeric(as.factor(dat$key)))
dat$altkey <- as.factor(dat$altkey)
dat$D <- as.logical(dat$D)
row.names(dat) <- paste(dat$key, dat$altkey, sep = ".")
Now the data looks like this:
key altkey A B C D
1.1 1 1 2.6 118.17 117 FALSE
1.2 1 2 1.4 117.11 115 FALSE
1.3 1 3 1.1 117.38 122 TRUE
1.4 1 4 24.6 NA 122 FALSE
1.5 1 5 48.6 91.90 122 FALSE
1.6 1 6 59.8 NA 122 FALSE
2.1 2 1 20.2 118.23 113 FALSE
2.2 2 2 2.5 123.67 120 TRUE
2.3 2 3 7.4 116.30 120 FALSE
2.4 2 4 2.8 118.86 120 FALSE
2.5 2 5 6.9 124.72 120 FALSE
2.6 2 6 2.5 123.81 120 FALSE
2.7 2 7 8.5 119.23 115 FALSE
And you can call mlogit() directly:
mlogit(D ~ A + B + C, dat,
chid.var = "key",
alt.var = "altkey",
choice = "D",
shape = "long")
Result:
Call:
mlogit(formula = D ~ A + B + C, data = dat, chid.var = "key", alt.var = "altkey", choice = "D", shape = "long", method = "nr", print.level = 0)
Coefficients:
2:(intercept) 3:(intercept) 4:(intercept) 5:(intercept) 6:(intercept)
10.7774 4.8129 5.2257 -17.2522 -7.7364
7:(intercept) A B C
10.0389 1.6010 2.7156 2.9888
JohnP,
I think the answer you are looking for is at maxabet. It says:
"If readers try to use R to calculate MLR which is introduced in Chapter 6, the following error message may occur:
Error in `row.names<-.data.frame ... (some data afterwards) duplicate 'row.names' are not allowed
This error is a problem of current version of R (which released in April 2011). The MLR will run only if the number of 'rows' ('runners' in our case) is the same in every race. Therefore one of the way is making some 'dummy horses' so that every race has 14 runners. Instead of making dummy runners, readers may either wait for R to solve this problem, or try some way to download an earlier version (I am using 2.9.1). "
So I guess you could use an older version of R or better still, fill the existing data with dummy values to complete each race. One thing that I would do is add a new variable for "field size" for each race. By throwing in dummies, but having the correct number of runners in a new column should take care of any field size variance.
Obviously the answers you get will be different to the book you are reading, but it will a good start to better handicapping :)
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