| Why doesn't this return the correct value? [message #58673] |
Thu, 14 February 2008 02:59 |
chloesharrocks
Messages: 16
Registered: January 2008
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Junior Member |
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Dear all
I currently have an array called good_index. Some of the elements are
> =0 and others are <0. I want to write a code that firstly finds how
many of these elements are greater than zero and use this number to
produce another array (called good_indexed_precip) with that number of
elements. Then I want it to search through each element of good_index
in turn. If upon searching it finds that the element is >=0 I want it
to find the value of that element in good_index. I then want to find
the data stored in the index given by that value in another array
called precip_change. The code I've written is below:
=====
counter_2 = 0
number = total(good_index ge 0, /int) ;this counts how many elements
in good_index are >= zero
print, number ;this gives the correct answer 6
FOR s=0, (N_ELEMENTS(good_index)-1) DO BEGIN
good_indexed_precip=fltarr(number)
IF good_index[s] ge 0 THEN BEGIN
good_indexed_precip[counter_2] = precip_change[good_index[s]]
counter_2++
ENDIF
ENDFOR
=====
Unfortunately, it then prints good_indexed_precip with all 6 elements
zero, even though the values of precip_change[good_index[s]] are non-
zero.
If I were to put in the data by hand, eg say
good_indexed_precip[0] = precip_change[good_index[0]]
good_indexed_precip[1] = precip_change[good_index[13]]
This works fine, so I can't see why my loop isn't working correctly.
I know that the 0th &1st element of good_index are both >=zero, yet if
I run the loop: FOR s=0, 1 DO BEGIN etc and print good_indexed_precip
it only has a non-zero value in the 1st element and not the 0th
element!
Thanks for all your help in advance.
Chloé
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