On 26/07/2010 2:56 PM, mirek wrote:
Hello,
In my script I would like to use a loop, which sorts the dataframe
according to different columns, pointed by the string variable.
id col1 col2 col3
1 10 0 4 8
2 11 1 2 2
3 12 0 8 3
4 13 0 5 5
Usually the order() function can be used like this:
sorted = mytable[order(column3) , ]
which results in properly sorted table:
id col1 col2 col3
2 11 1 2 2
3 12 0 8 3
4 13 0 5 5
1 10 0 4 8
But when trying to use a string variable instead of "column3" name:
columnname = "column3"
sorted = mytable[order(columnname) , ]
this command is not properly evaluated and the effect is somewhat strange.
The argument to order() should be a vector whose sort order is to be
returned. So you just need to extract one column from the dataframe, e.g.
column <- mytable[, columnname]
sorted <- mytable[order(column) , ]
Duncan Murdoch
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