[R] Calculating percentage Missing value for variables using one object

[David Winsemius]

It looks to me that you should be using the table or the xtabs  
function. You have apparently already decided not to use NA for  
missing values, so the instances in which variable1 == "" you should  
get counts with those functions:

dft <- data.frame(var1 = sample(c("", "this", "that", "and"), 120,  
replace=TRUE),
                dt = sample( seq(as.Date("2006-01-01"),  
as.Date("2007-12-31"), by="months"),
                            120, replace=TRUE))

mo.tbl <- xtabs( ~var1+ dt, data=dft)      # the =="" entry is the  
first row

 > mo.tbl[1,]
2006-01-01 2006-02-01 2006-03-01 2006-04-01 2006-05-01 2006-06-01  
2006-07-01
          2          1          1          2          2           
3          1
2006-08-01 2006-09-01 2006-10-01 2006-11-01 2006-12-01 2007-01-01  
2007-02-01
          0          1          1          1          2           
1          2
2007-03-01 2007-04-01 2007-05-01 2007-06-01 2007-07-01 2007-08-01  
2007-09-01
          2          2          2          0          1           
3          4
2007-10-01 2007-11-01 2007-12-01
          1          3          2

x <- seq(as.Date("2006-01-01"), as.Date("2007-03-31"), by="months")
plot(mo.tbl[1,]~x)

-- 
David Winsemius

On Mar 24, 2009, at 2:58 AM, Shreyasee wrote:

> Hi,
>
> I have a dataset in which there are in all 250 variables and for each
> variable the data is entered over the months.
> I need to calculate the percentage of missing values for each  
> variable over
> each month and then plot a graph for that.
> I am running the following code for doing the same
>
> *ds <- read.csv(file="filepath", header=TRUE)
> attach(ds)
> may <- length(variable1[variable1==""]) / length(dos[dos=="May-06"])  
> * 100
> jun <- length(variable1[variable1==""]) /  
> length(dos[dos=="June-06"]) * 100
> .
> .
> .
> var1 <- c(may, jun, ...........)
> x <- seq(as.Date("2006-01-01"), as.Date("2007-03-31"), by="months")
> plot(var1~x)*
>
> So likewise I am calculating the percentage of missing values for each
> variable for each month using different variables and storing the  
> values in
> those variables and then combining those variables in one object for
> plotting the graph.
> I need to know, whether can I combine all the variables from that  
> dataset in
> one object and calculate the missing values percentage over months  
> together,
> instead of creating different variables for each month and then  
> combining
> them.
> Also, after doing that, I need to plot the graph for each variable and
> combine it in a single pdf file.
>
> I highly appreciate all your help.
>
> Thanks,
> Shreyasee
>
> 	[[alternative HTML version deleted]]
>
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David Winsemius, MD
Heritage Laboratories
West Hartford, CT