Using mapply to create sequence objects in R/TraMineR?

Question

I am running the code below to generate a list of TraMineR sequence objects. The dataset can be found [here][1].

library(TraMineR)
sequences <- read.csv(file = "event-stream-20-l-m.csv", header = TRUE, nrows=10)
repo_names = colnames(sequences)

# 1. Loop across and define the 24 sequence objects & store them in sequence_objects
colpicks <- seq(10,240,by=10)
sequence_objects <- mapply(function(start,stop) seqdef(sequences[,start:stop]),
                           colpicks - 9, colpicks)

However, if I run:

test <- sequence_objects[1]
seqdist(test, indel=1, with.missing=FALSE, norm="maxdist")

The error message I receive is:

Error:  [!] data is not a state sequence object, use 'seqdef' function to create one

How can it be that the mapply using seqdef does not create a list of sequence objects?

Answer 1

mapply by default simplifies the return value.

As per the comment in the previous question, try including SIMPLIFY=FALSE in the mapply call.