Include zero frequencies in frequency table for Likert data

Question

I have a dataset with responses to a Likert item on a 9pt scale. I would like to create a frequency table (and barplot) of the data but some values on the scale never occur in my dataset, so table() removes that value from the frequency table. I would like it instead to present the value with a frequency of 0. That is, given the following dataset

# Assume a 5pt Likert scale for ease of example
data <- c(1, 1, 2, 1, 4, 4, 5)

I would like to get the following frequency table without having to manually insert a column named 3 with the value 0.

1 2 3 4 5 
3 1 0 2 1

I'm new to R, so maybe I've overlooked something basic, but I haven't come across a function or option that gives the desired result.

Answer 1

EDIT:

tabular produces frequency tables while table produces contingency tables. However, to get zero frequencies in a one-dimensional contingency table as in the above example, the below code still works, of course.

---

This question provided the missing link. By converting the Likert item to a factor, and explicitly specifying the levels, levels with a frequency of 0 are still counted

data <- factor(data, levels = c(1:5))
table(data)

produces the desired output

Answer 2

table produces a contingency table, while tabular produces a frequency table that includes zero counts.

tabulate(data)
# [1] 3 1 0 2 1

Another way (if you have integers starting from 1 - but easily modifiable for other cases):

setNames(tabulate(data), 1:max(data))  # to make the output easier to read
# 1 2 3 4 5 
# 3 1 0 2 1