@Override
Val apply(Env env, Env.StackHelp stk, AST asts[]) {
Val v = stk.track(asts[1].exec(env));
if (v instanceof ValRow) {
ValRow vv = (ValRow) v;
return vv.slice(asts[2].columns(vv._names));
}
Frame fr = v.getFrame();
int[] cols = asts[2].columns(fr.names());
Frame fr2 = new Frame();
if (cols.length == 0) { // Empty inclusion list?
} else if (cols[0] >= 0) { // Positive (inclusion) list
if (cols[cols.length - 1] > fr.numCols())
throw new IllegalArgumentException(
"Column must be an integer from 0 to " + (fr.numCols() - 1));
for (int col : cols) fr2.add(fr.names()[col], fr.vecs()[col]);
} else { // Negative (exclusion) list
fr2 = new Frame(fr); // All of them at first
Arrays.sort(cols); // This loop depends on the values in sorted order
for (int col : cols)
if (0 <= -col - 1 && -col - 1 < fr.numCols()) fr2.remove(-col - 1); // Remove named column
}
return new ValFrame(fr2);
}
/** Removes a numbered column. */
public Vec[] remove(int[] idxs) {
for (int i : idxs) if (i < 0 || i > _vecs.length) throw new ArrayIndexOutOfBoundsException();
Arrays.sort(idxs);
Vec[] res = new Vec[idxs.length];
Vec[] rem = new Vec[_vecs.length - idxs.length];
String[] names = new String[rem.length];
Key[] keys = new Key[rem.length];
int j = 0;
int k = 0;
int l = 0;
for (int i = 0; i < _vecs.length; ++i)
if (j < idxs.length && i == idxs[j]) {
++j;
res[k++] = _vecs[i];
} else {
rem[l] = _vecs[i];
names[l] = _names[i];
keys[l] = _keys[i];
++l;
}
_vecs = rem;
_names = names;
_keys = keys;
assert l == rem.length && k == idxs.length;
return res;
}