Question

I have a data frame with distances between start and end points. Start points are in rows, end points are in columns. Now I want to have them printed each one by one (startpoint endpoint distance newline). Missing values (NAs) should be omitted.

This is my data frame:

          EndPoint
    StartPoint TX001    TX002    TX003
         TX002  37.4       NA       NA
         TX003    NA 14.78704       NA
         TX005    NA       NA 60.78947

What I want to get is:

    TX002 TX001 37.4
    TX003 TX002 14.78704
    TX005 TX003 60.78947

Any help is greatly appreciated.

Sugi

Answer 1

If I’ve missed the mark, please use dput to provide a sample of your data. However, assuming your data looks like this:

dat <- structure(list(StartPoint = c("TX002", "TX003", "TX005"), TX001 = c(37.4, 
NA, NA), TX002 = c(NA, 14.78704, NA), TX003 = c(NA, NA, 60.78947
)), .Names = c("StartPoint", "TX001", "TX002", "TX003"), class = "data.frame", row.names = c(NA, 
-3L))

You can use melt from the reshape2 package and then drop the extra rows with na.omit.

> na.omit(melt(dat, 
               id.var='StartPoint', 
               variable.name='EndPoint', 
               value.name='Distance'))

  StartPoint EndPoint Distance
1      TX002    TX001 37.40000
5      TX003    TX002 14.78704
9      TX005    TX003 60.78947