Create frequency tables for multiple factor columns in R
I am a novice in R. I am compiling a separate manual on the syntax for the common functions/features for my work. My sample dataframe as follows:
x.sample <-
structure(list(Q9_A = structure(c(5L, 3L, 5L, 3L, 5L, 3L, 1L,
5L, 5L, 5L), .Label = c("Impt", "Neutral", "Not Impt at all",
"Somewhat Impt", "Very Impt"), class = "factor"), Q9_B = structure(c(5L,
5L, 5L, 3L, 5L, 5L, 3L, 5L, 3L, 3L), .Label = c("Impt", "Neutral",
"Not Impt at all", "Somewhat Impt", "Very Impt"), class = "factor"),
Q9_C = structure(c(3L, 5L, 5L, 3L, 5L, 5L, 3L, 5L, 5L, 3L
), .Label = c("Impt", "Neutral", "Not Impt at all", "Somewhat Impt",
"Very Impt"), class = "factor")), .Names = c("Q9_A", "Q9_B",
"Q9_C"), row.names = c(NA, 10L), class = "data.frame")
> x.sample
Q9_A Q9_B Q9_C
1 Very Impt Very Impt Not Impt at all
2 Not Impt at all Very Impt Very Impt
3 Very Impt Very Impt Very Impt
4 Not Impt at all Not Impt at all Not Impt at all
5 Very Impt Very Impt Very Impt
6 Not Impt at all Very Impt Very Impt
7 Impt Not Impt at all Not Impt at all
8 Very Impt Very Impt Very Impt
9 Very Impt Not Impt at all Very Impt
10 Very Impt Not Impt at all Not Impt at all
My original dataframe has 21 columns.
If I want to find the mean (treating this as an ordinal variable):
> sapply(x.sample,function(x) mean(as.numeric(x), na.rm=TRUE))
Q9_A Q9_B Q9_C
4.0 4.2 4.2
I would like to tabulate a frequency table for ALL the variables in my dataframe. I searched the internet and many forums and saw that the nearest command to do this is using sapply. But when I did it, it gave all 0s.
> sapply(x.sample,function(x) table(factor(x.sample, levels=c("Not Impt at all", "Somewhat Impt", "Neutral", "Impt", "Very Impt"), ordered=TRUE)))
Q9_A Q9_B Q9_C
Not Impt at all 0 0 0
Somewhat Impt 0 0 0
Neutral 0 0 0
Impt 0 0 0
Very Impt 0 0 0
QUESTION How can I make use of sapply to tabulate a frequency chart as per the above table for all the columns (that are factors) in a dataframe?
PS So sorry if this seems trivia but I have searched for 2 days without an answer and trying all possible combinations. Maybe I didn't search hard enough =(
Thanks very much.
Answer
You were nearly there. Just one small change in your function would have got you there. The x in function(x) ... needs to be passed through to the table() call:
levs <- c("Not Impt at all", "Somewhat Impt", "Neutral", "Impt", "Very Impt")
sapply(x.sample, function(x) table(factor(x, levels=levs, ordered=TRUE)))
A little re-jig of the code might make it a bit easier to read too:
sapply(lapply(x.sample,factor,levels=levs,ordered=TRUE), table)
# Q9_A Q9_B Q9_C
#Not Impt at all 3 4 4
#Somewhat Impt 0 0 0
#Neutral 0 0 0
#Impt 1 0 0
#Very Impt 6 6 6