| Re: where function not finding value [message #90562 is a reply to message #88265] |
Tue, 10 March 2015 11:12   |
Jahvasc
Messages: 9
Registered: March 2014
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Junior Member |
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Hi, guys,
I have a similar problem but I'm comparing intervals to avoid the float-precision problem. Still, I can't get the right answer...
I have a vector with 500 values ranging from 0.01 to 0.4 (0.01 to 0.1 by 0.01; 0.2 to 0.4 by 0.1).
When I use the histogram function I get a certain number of counts for all intervals:
79 57 48 44 43 43
30 43 31 34 25 14 9
i.e., the value 0.01 appears 79 times, the value 0.02, 57 times, etc.
However, when I use the where function, I get some "holes". This is the bit of the code I'm using:
mmod=[findgen(10)*0.01 + 0.01,findgen(3)*0.1 + 0.2]
massi=0.
for j=0,12 do begin
a=where(mass gt massi and mass le mmod(j),count)
print,massi,mmod(j),count
massi=mmod(j)
endfor
In this case I get the following numbers:
0.00000 0.0100000 79
0.0100000 0.0200000 57
0.0200000 0.0300000 48
0.0300000 0.0400000 44
0.0400000 0.0500000 0
0.0500000 0.0600000 43
0.0600000 0.0700000 73
0.0700000 0.0800000 43
0.0800000 0.0900000 0
0.0900000 0.100000 31
0.100000 0.200000 59
0.200000 0.300000 14
0.300000 0.400000 9
When I manually try, for example,
a=where(mass gt 0.04 and mass le 0.05,count)
print,count
I get count=43. What's is going on?
Thanks,
Jaqueline
On Thursday, April 3, 2014 at 7:44:00 PM UTC+2, Marsha Boggs wrote:
> Hello,
> I have a problem with a particular call to the 'where' function that I don't understand.
>
> I have the following code snippet:
>
> print, 'dncom.dt.julian is: ', dncom.dt.julian
> print, 'dt.julian is: ', dt.julian
>
> ; end debug
> i = where(dncom.dt.julian eq dt.julian, count) ; Find index of requested date & time
> if count gt 0 then begin
> data = dncom(i)
> ; debug stuff
> print, 'the data ',data
> endif else begin
> print, 'ncom_table.pro: desired or most recent time not found'
> retall
> return
> endelse
>
>
> and it says the requested value is not there everytime..
>
> This is the output
>
> dncom.dt.julian is: 95528.427 95528.438 95528.448
> 95528.458 95528.469 95528.479 95528.490
> 95528.500 95528.510 95528.521 95528.531
> 95528.542 95528.552 95528.562 95528.573
> 95528.583 95528.594 95528.604 95528.615
> 95528.625 95528.635 95528.646 95528.656
> 95528.667 95528.677 95528.688 95528.698
> 95528.708 95528.719 95528.729 95528.740
> 95528.750 95528.760 95528.771 95528.781
> 95528.792 95528.802 95528.812 95528.823
> 95528.833 95528.844 95528.854 95528.865
> 95528.875 95528.885 95528.896 95528.906
> 95528.917 95528.927 95528.938 95528.948
> 95528.958 95528.969 95528.979 95528.990
> 95529.000 95529.010 95529.021 95529.031
> 95529.042 95529.052 95529.062 95529.073
> 95529.083 95529.094 95529.104 95529.115
> 95529.125 95529.135 95529.146 95529.156
> 95529.167 95529.177 95529.188 95529.198
> 95529.208 95529.219 95529.229 95529.240
> 95529.250 95529.260 95529.271 95529.281
> 95529.292 95529.302 95529.312 95529.323
> 95529.333 95529.344 95529.354 95529.365
> 95529.375 95529.385 95529.396 95529.406
> 95529.417 95529.427 95529.438 95529.448
> 95529.458 95529.469 95529.479 95529.490
> 95529.500 95529.510 95529.521 95529.531
> 95529.542 95529.552 95529.562 95529.573
> 95529.583 95529.594 95529.604 95529.615
> 95529.625 95529.635 95529.646 95529.656
> 95529.667 95529.677 95529.688 95529.698
> 95529.708 95529.719 95529.729 95529.740
> 95529.750 95529.760 95529.771 95529.781
> 95529.792 95529.802 95529.812 95529.823
> 95529.833 95529.844 95529.854 95529.865
> 95529.875 95529.885 95529.896 95529.906
> 95529.917 95529.927 95529.938 95529.948
> 95529.958 95529.969 95529.979 95529.990
> 95530.000 95530.010 95530.021 95530.031
> 95530.042 95530.052 95530.062 95530.073
> 95530.083 95530.094 95530.104 95530.115
> 95530.125 95530.135 95530.146 95530.156
> 95530.167 95530.177 95530.188 95530.198
> 95530.208 95530.219 95530.229 95530.240
> 95530.250 95530.260 95530.271 95530.281
> 95530.292 95530.302 95530.312 95530.323
> 95530.333 95530.344 95530.354 95530.365
> 95530.375 95530.385 95530.396 95530.406
> 95530.417 95530.427
>
> dt.julian is: 95530.427
> ncom_table.pro: desired or most recent time not found
>
>
> The value is there, It is the last value in the array.
> Any idea what is going on?
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