in src/main/java/com/twitter/sbf/core/SparseBinaryMatrix.java [360:368]
int minColSizeAboveZero() {
int min = Integer.MAX_VALUE;
for (IntSet col : this.cols) {
if (col.size() > 0 && col.size() < min) {
min = col.size();
}
}
return min;
}