将大小不同的行变成列

Question

I am reading in a data file with many different rows, all of which can have different lengths like so:

dataFile <- read.table("file.txt", as.is=TRUE);

The rows can be as follows:

1 5 2 6 2 1
2 6 24
2 6 1 5 2 7 982 24 6
25 2

I need the rows to be transformed into columns. I'll be then using the columns for a violin plot like so:

names(dataCol)[1] <- "x";
jpeg("violinplot.jpg", width = 1000, height = 1000);
do.call(vioplot,c(dataCol,))
dev.off()

I'm assuming there will be an empty string/placeholder for any column with fewer entries than the column with the maximum number of entries. How can it be done?

Answer 1

Use the fill = TRUE argument in read.table . Then to change rows to columns, use t to transpose. Using your data this would look like...

df <- read.table( text = "1 5 2 6 2 1
2 6 24
2 6 1 5 2 7 982 24 6
25 2
" , header = FALSE , fill = TRUE )

df
#  V1 V2 V3 V4 V5 V6  V7 V8 V9
#1  1  5  2  6  2  1  NA NA NA
#2  2  6 24 NA NA NA  NA NA NA
#3  2  6  1  5  2  7 982 24  6
#4 25  2 NA NA NA NA  NA NA NA

t(df)
#   [,1] [,2] [,3] [,4]
#V1    1    2    2   25
#V2    5    6    6    2
#V3    2   24    1   NA
#V4    6   NA    5   NA
#V5    2   NA    2   NA
#V6    1   NA    7   NA
#V7   NA   NA  982   NA
#V8   NA   NA   24   NA
#V9   NA   NA    6   NA

Answer 2

EDIT: apparently read.table has a fill=TRUE option, which is WAYYYY easier than my answer.

I've never used vioplot before, and that seems like a weird way to make a function call (instead of something like vioplot(dataCol) ), but I have worked with ragged arrays before, so I'll try that.

Have you read the data in yet? That tends to be the hardest part. The code below reads the above data from a file called temp.txt into a matrix called out2

file = 'temp.txt'
dat = readChar(file,file.info(file)$size)
split1 = strsplit(dat,"\n")
split2 = strsplit(split1[[1]]," ")
n = max(unlist(lapply(split2,length)))
out=matrix(nrow=n,ncol=length(split2))
tFun = function(i){
    vect = as.numeric(split2[[i]])
    length(vect)=n
    out[,i]=vect
}
out2 = sapply(1:length(split2),tFun)

I'll try and explain what I've done: the first step is to read in every character via readChar . You then split the lines, then the elements within each line to get the list split2 , where each element of the list is a row of the input file.

From there you create a blank matrix that would be the right size for your data, then iterate through the list and assign each element to a column.

It's not pretty, but it works!