public static SparseIntArray histogram(int[] vector, int W) {
final SparseIntArray hist = new SparseIntArray(W);
for (int i : vector) {
hist.inc(i);
}
return hist;
}
/** Convert a dense array to a sparse array */
public static SparseIntArray fromArray(int[] arr) {
SparseIntArray sa = new SparseIntArray(arr.length);
for (int i = 0; i < arr.length; i++) {
if (arr[i] != 0) {
sa.put(i, arr[i]);
}
}
return sa;
}
@Override
public Vector<Integer> subvector(int offset, int length) {
final SparseIntArray sv = new SparseIntArray(n);
final ObjectIterator<Entry> iter = int2IntEntrySet().fastIterator();
while (iter.hasNext()) {
final Entry e = iter.next();
if (e.getIntKey() >= offset && e.getIntKey() < offset + length) {
sv.put(e.getIntKey(), e.getIntValue());
}
}
return sv;
}
public static SparseIntArray fromBinary(InputStream stream, int W) throws IOException {
final DataInputStream dis = new DataInputStream(stream);
final SparseIntArray arr = new SparseIntArray(W);
while (dis.available() > 0) {
try {
arr.inc(dis.readInt());
} catch (EOFException x) {
break;
}
}
return arr;
}
public static SparseIntArray fromFrequencyString(String string, int n)
throws VectorFormatException {
final String[] entries = string.split("\\s+");
final SparseIntArray array = new SparseIntArray(n);
for (String entry : entries) {
try {
array.inc(Integer.parseInt(entry));
} catch (NumberFormatException x) {
throw new VectorFormatException(x);
}
}
return array;
}
/**
* Create from a string of the form "idx=val,...,idx=val"
*
* @param string The string
* @param n The length of the array
* @param defaultValue The default value
* @param sep The seperator
* @return The array object
* @throws SparseIntArrayFormatException If the string is not formatted as a sparse array
*/
public static SparseIntArray fromString(String string, int length, int defaultValue, String sep)
throws VectorFormatException {
String[] entries = string.split(sep);
final SparseIntArray SparseIntArray = new SparseIntArray(length);
for (String entry : entries) {
if (entry.matches("\\s*")) {
continue;
}
String[] values = entry.split("=");
if (values.length != 2) {
throw new VectorFormatException("Bad sparse array value " + entry);
}
SparseIntArray.put(new Integer(values[0]), new Integer(values[1]));
}
return SparseIntArray;
}