Visualising survey responses

#1
Hi there,

We have got back the results of a survey and I was hoping someone could help with R code to visualise the results. There were about 20 questions in total with likert scales. We'd like to view the responses by age groups and gender. I think a mosaic plot might be the best but I can't seem to get data in the right form. At the moment each row is a participant and each column is a question. Is there a simple way to create the graph?

I've tried structable(data[,1:20]~data$sex) but that gives an "invalid type" error. Could someone please help?

Thanks in advance.