[R] Help with the Error Message in R "Error in 1:nchid : result would be too long a vector"

Rahul Chakraborty ch@kr@r@hu| @end|ng |rom gm@||@com
Tue Sep 22 07:20:46 CEST 2020

Hello David and everyone,

I am really sorry for not abiding by the specific guidelines in my
prior communications. I tried to convert the present email in plain
text format (at least it is showing me so in my gmail client). I have
also converted the xlsx file into a csv format with .txt extension.

So, my problem is I need to run panel mixed logit regression for a
choice model. There are 3 alternatives, 9 questions for each
individual and 516 individuals in data. I have created a csv file in
long format from the survey questionnaire. Apart from the alternative
specific variables I have many individual specific variables and most
of these are dummies (dummy coded). I will use subsets of these in my
alternative model specifications. So, in my data I have 100 columns
with 13932 rows (3*9*516). After reading the csv file and creating a
dataframe 'mydata' I used the following command for mlogit.

mldata1<- mlogit.data(mydata, shape = "long", alt.var = "Alt_name",
choice = "Choice_binary", id.var = "IND")

It gives me the same error message- Error in 1:nchid : result would be
too long a vector.

The attached file (csv file with .txt extension) is an example of 2
individuals each with 3 questions. I have also reduced the number of
columns to 57. Now, there are 18 rows. But still if I use the same
command on my new data I get the same error message. Can anyone please
help me out with this? Because of this error I am stuck at the
dataframe level.

Thanks in advance.

Rahul Chakraborty

On Tue, Sep 22, 2020 at 4:50 AM David Winsemius <dwinsemius using comcast.net> wrote:
> @Rahul;
> You need to learn to post in plain text and attachments may not be xls
> or xlsx. They need to be text files. And even if they are comma
> separated files and text, they still need to be named with a txt extension.
> I'm the only one who got the xlsx file. I got the error regardless of
> how many column I omitted, so my gues was possibly incorrect. But I did
> RTFM. See ?mlogit.datadfi The mlogit.data function is deprecated and you
> are told to use the dfidx function. Trying that you now get an error
> saying: " the two indexes don't define unique observations".
>  > sum(duplicated( dfrm[,1:2]))
> [1] 12
>  > length(dfrm[,1])
> [1] 18
> So of your 18 lines in the example file, most of them appear to be
> duplicated in their first two rows and apparently that is not allowed by
> dfidx.
> Caveat: I'm not a user of the mlogit package so I'm just reading the
> manual and possibly coming up with informed speculation.
> Please read the Posting Guide. You have been warned. Repeated violations
> of the policies laid down in that hallowed document will possibly result
> in postings being ignored.

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