| edit a large dataset [message #56102] |
Wed, 03 October 2007 07:48 |
queiny
Messages: 15
Registered: November 2005
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Junior Member |
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Hi, I have a large dataset (>1e7 records). One field of the record is
a string 'landuse'. Now I want to add one more field based on the
'landuse', i.e., if it is 'forest', then add 'aa', if it is 'urban',
then add 'bb', etc.. Since there are more than 20 different landuse,
use 'if-then', or 'case' for each record will be quite inefficient.
I am thinking of 'sort' the records based on 'landuse', and then use
'uniq' to locate the starting point and number of records for each
'landuse' type and add the new fields accordingly. But how could I go
back to the original order afterward?
a=sort(data_orig)
data_sorted=data_orig(a)
;processing based on 'data_sorted'
but how could I go back the order of 'data_orig'? Is there a inversion
of 'sort'.
Thanks,
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