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

You were told two things about your code:


1) mlogit.data is deprecated by the package authors, so use dfidx.

2) dfidx does not allow duplicate ids in the first two columns.


Which one of those are you asserting is not accurate?


--

David.

On 9/21/20 10:20 PM, Rahul Chakraborty wrote:

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.


Regards,
Rahul Chakraborty

On Tue, Sep 22, 2020 at 4:50 AM David Winsemius <dwinsemius at 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.