You posted an approach in your question which was not bad. Here’s a smiliar approach: new <- df # create a copy of df # using lapply, loop over columns and match values to the look up table. store in “new”. new[] <- lapply(df, function(x) look$class[match(x, look$pet)]) An alternative approach which will be faster is: … Read more
It is because name lookup stops if it finds a name in one of your bases. It won’t look beyond in other bases. The function in B shadows the function in A. You have to re-declare the function of A in the scope of B, so that both functions are visible from within B and … Read more
The entry API is designed for this. In manual form, it might look like let values = match map.entry(key) { Entry::Occupied(o) => o.into_mut(), Entry::Vacant(v) => v.insert(default), }; One can use the briefer form via Entry::or_insert_with: let values = map.entry(key).or_insert_with(|| default); If default is already computed, or if it’s OK/cheap to compute even when it isn’t … Read more
You create a new key/value pair on a dictionary by assigning a value to that key d = {‘key’: ‘value’} print(d) # {‘key’: ‘value’} d[‘mynewkey’] = ‘mynewvalue’ print(d) # {‘key’: ‘value’, ‘mynewkey’: ‘mynewvalue’} If the key doesn’t exist, it’s added and points to that value. If it exists, the current value it points to is … Read more