Hi all!

I'm trying to do a heatmap with `plink`'s output for IBD calculation (`.genome`file).
This file has several columns, but only three are important to me, so my parsed input format looks like this:

    IID1	IID2	PI_HAT
    ID1	    ID2	    0.0163
    ID1	    ID3	    0
    ID1	    ID4	    0.0155
    ID2	    ID1	    0.0096
    ID2	    ID3	    0.0125
    ID2     ID4     0.475
    ...

I would like to do a heatmap with the PIHAT values for all my IDs (I have hundreds). To my understanding, `R`asks for a matrix as input for the plot, but I'm not able to parse this input into the correct format (I actually get the heatmap, but all the values are wrong). Could someone please give me advice or if there's another way to do the plot, I'd be as well to try it. Thank you very much in advance!
Input data for `heatmap` should be numeric matrix, your data is long format data, we need to reshape it to wide, then convert to matrix for plotting, see example:

    library(reshape2)
    
    # example data
    df1 <- read.table(text = "IID1    IID2    PI_HAT
    ID1     ID2     0.0163
    ID1     ID3     0
    ID1     ID4     0.0155
    ID2     ID1     0.0096
    ID2     ID3     0.0125
    ID2     ID4     0.475", header = TRUE, stringsAsFactors = FALSE)
    
    
    #convert long-to-wide
    x <- dcast(df1, IID1 ~ IID2, value.var = "PI_HAT")
    
    # convert to matrix with column AND rownames
    myM <- as.matrix(x[ , -1 ])
    row.names(myM) <- x$IID1
    
    # I am converting all NAs to 0, reconsider if this is suitable in your case.
    myM[ is.na(myM) ] <- 0
    
    #then plot
    heatmap(myM)

<a href="https://imgur.com/jvpHnRq"><img src="https://i.imgur.com/jvpHnRq.jpg" title="source: imgur.com" /></a>