This function allows to generate a frequency table from a multiple choices question. The question's answers must be stored in a series of binary variables.
multi.table(df, true.codes = NULL, weights = NULL, digits = 1, freq = TRUE)data frame with the binary variables
optional list of values considered as 'true' for the tabulation
optional weighting vector
number of digits to keep in the output
add a percentage column
Object of class table.
The function is applied to a series of binary variables, each one corresponding to a choice of the question. For example, if the question is about seen movies among a movies list, each binary variable would correspond to a movie of the list and be true or false depending of the choice of the answer.
By default, only '1' and 'TRUE' as considered as 'true' values fro the binary variables,
and counted in the frequency table. It is possible to specify other values to be counted
with the true.codes argument. Note than '1' and 'TRUE' are always considered as
true values even if true.codes is provided.
If freq is set to TRUE, a percentage column is added to the resulting table. This
percentage is computed by dividing the number of TRUE answers for each value by the total
number of (potentially weighted) observations. Thus, these percentages sum can be greater
than 100.
## Sample data frame
set.seed(1337)
sex <- sample(c("Man","Woman"),100,replace=TRUE)
jazz <- sample(c(0,1),100,replace=TRUE)
rock <- sample(c(TRUE, FALSE),100,replace=TRUE)
electronic <- sample(c("Y","N"),100,replace=TRUE)
weights <- runif(100)*2
df <- data.frame(sex,jazz,rock,electronic,weights)
## Frequency table on 'music' variables
multi.table(df[,c("jazz", "rock","electronic")], true.codes=list("Y"))
#> n %multi
#> jazz 47 47
#> rock 49 49
#> electronic 51 51
## Weighted frequency table on 'music' variables
multi.table(df[,c("jazz", "rock","electronic")], true.codes=list("Y"), weights=df$weights)
#> n %multi
#> jazz 43.6 47.2
#> rock 45.2 48.9
#> electronic 47.0 50.9
## No percentages
multi.table(df[,c("jazz", "rock","electronic")], true.codes=list("Y"), freq=FALSE)
#> jazz rock electronic
#> 47 49 51