Re: Question about data types

Gina,

If you are using NCL 5.2.0 or later version, the easy way is to use
"tofloat(xxx)",
which will convert any NCL data type to float.

Wei

huangwei@ucar.edu
VETS/CISL
National Center for Atmospheric Research
P.O. Box 3000 (1850 Table Mesa Dr.)
Boulder, CO 80307-3000 USA
(303) 497-8924

On Sep 14, 2010, at 9:29 AM, Gina Henderson wrote:

> Hi there,
>
> I have a question about the correct function to use to convert a
> hexadecimal input array to type float. If I use the function
> "stringtointeger" to convert it I get the correct data ranges (from
> 0-255) but I also get the following warning:
>
> warning:Argument 0 of the current function or procedure was coerced
> to the appropriate type and thus will not change if the function or
> procedure modifies its value
>
> If I use "byte2flt" to convert the data, I get no warning message
> but my data range then only goes from 0-254 and all grids that were
> value = 255 are now set to another value which I am pretty sure is 0.
>
> The variable summary of the raw data array is included below. My
> question is, should I be worried about the warning I get when
> converting the data using "stringtointeger", as this method
> maintains the original data more correctly that reading the data in
> and then converting it using "byte2flt".
>
> Any suggestions or comments would be greatly appreciated.
> Thanks, Gina.
>
> ----------------------------------------------------------------------
> printVarSummary of original data array:
>
> Variable: modis_per_byte
> Type: byte
> Total Size: 25920000 bytes
> 25920000 values
> Number of Dimensions: 2
> Dimensions and sizes: [YDim_MOD_CMG_Snow_5km | 3600] x
> [XDim_MOD_CMG_Snow_5km | 7200]
> Coordinates:
> Number Of Attributes: 13
> long_name : Daily snow extent, global at 5km
> units : none
> format : I3
> coordsys : latitude, longitude
> valid_range : ( 0x00, 0x64 )
> _FillValue : 0xff
> Mask_value : 0xfe
> Night_value : 0x6f
> Cell_resolution : 0.05 deg
> Water_mask_land_threshold____ : 12
> Antarctica_snow_note : Antarctica deliberately mapped as snow
> Key : 0-100=percent of snow in cell, 107=lake ice, 111=night,
> 250=cloud obscured water, 253=data not mapped, 254=water mask, 255=f
> ll
> hdf_name : Day_CMG_Snow_Cover
> (0)
> (0) Daily snow extent, global at 5km: min=0x00 max=0xfe
>
>
>
>
>
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Received on Tue Sep 14 08:52:03 2010