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NOTICE: This version of the NSF Unidata web site (archive.unidata.ucar.edu) is no longer being updated.
Current content can be found at unidata.ucar.edu.
To learn about what's going on, see About the Archive Site.
Hi guys -We have been collaborating for awhile now on various projects with developers from the Indian Space Research Organization (ISRO). One of their guys, Ghansham Sangar, reported what looks like a bug in some static utilities in DataUtil. After
looking them over, I concur.It looks like the utilities toFloatarray(Array a) and toDoubleArray(Array a) are not handling unsigned data. Since Java never had support for unsigned byte, etc. types, you always have to do a little futzing when converting unsigned values.
As an example, here is how I would modify the current toFloatArray() method.Please look into getting this change in the library and let me know if you need
more info. Thanks Julien and Yuan!
/**
* Get the 1D values for an array as floats.
*
* @param arr Array of values
* @return float representation
*/
public static float[] toFloatArray(Array arr) {
Object dst = arr.get1DJavaArray(float.class);
Class fromClass = dst.getClass().getComponentType();
if (fromClass.equals(float.class)) {
//It should always be a float
return (float[]) dst;
} else {
float[] values = new float[(int) arr.getSize()];
boolean isUnsigned = arr.isUnsigned();
if (fromClass.equals(byte.class)) {
byte[] fromArray = (byte[]) dst;
for (int i = 0; i < fromArray.length; ++i) {
if (isUnsigned) {
values[i] = (int) fromArray[i] & 0xFF;
} else {
values[i] = fromArray[i];
}
}
} else if (fromClass.equals(short.class)) {
short[] fromArray = (short[]) dst;
for (int i = 0; i < fromArray.length; ++i) {
if (isUnsigned) {
values[i] = (int) fromArray[i] & 0xFFFF;
} else {
values[i] = fromArray[i];
}
}
} else if (fromClass.equals(int.class)) {
int[] fromArray = (int[]) dst;
for (int i = 0; i < fromArray.length; ++i) {
if (isUnsigned) {
values[i] = (long) fromArray[i] & 0xFFFFFFFF;
} else {
values[i] = fromArray[i];
}
}
} else if (fromClass.equals(double.class)) {
double[] fromArray = (double[]) dst;
for (int i = 0; i < fromArray.length; ++i) {
values[i] = (float) fromArray[i];
}
} else {
throw new IllegalArgumentException("Unknown array type:"
+ fromClass.getName());
}
return values;
}
}
--
Tommy Jasmin
Space Science and Engineering Center
University of Wisconsin, Madison
1225 West Dayton Street, Madison, WI 53706
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