For very small collections the difference is going to be negligible. At the low end of your range (500k items) you will start to see a difference if you’re doing lots of lookups. A binary search is going to be O(log n), whereas a hash lookup will be O(1), amortized. That’s not the same as … Read more
If I understand your question correctly, here are four methods to do the equivalent of Excel’s VLOOKUP and fill down using R: # load sample data from Q hous <- read.table(header = TRUE, stringsAsFactors = FALSE, text=”HouseType HouseTypeNo Semi 1 Single 2 Row 3 Single 2 Apartment 4 Apartment 4 Row 3″) # create a … 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
Yes, the list type is a good approximation. You can use names() on your list to set and retrieve the ‘keys’: > foo <- vector(mode=”list”, length=3) > names(foo) <- c(“tic”, “tac”, “toe”) > foo[[1]] <- 12; foo[[2]] <- 22; foo[[3]] <- 33 > foo $tic [1] 12 $tac [1] 22 $toe [1] 33 > names(foo) … 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
It’s a cross between an IGrouping and a dictionary. It lets you group items together by a key, but then access them via that key in an efficient manner (rather than just iterating over them all, which is what GroupBy lets you do). For example, you could take a load of .NET types and build … Read more
Use the valueOf method which is automatically created for each Enum. Verbosity.valueOf(“BRIEF”) == Verbosity.BRIEF For arbitrary values start with: public static Verbosity findByAbbr(String abbr){ for(Verbosity v : values()){ if( v.abbr().equals(abbr)){ return v; } } return null; } Only move on later to Map implementation if your profiler tells you to. I know it’s iterating over … Read more
loc: only work on index iloc: work on position at: get scalar values. It’s a very fast loc iat: Get scalar values. It’s a very fast iloc Also, at and iat are meant to access a scalar, that is, a single element in the dataframe, while loc and iloc are ments to access several elements … Read more
How about the List.FindIndex Method: int index = myList.FindIndex(a => a.Prop == oProp); This method performs a linear search; therefore, this method is an O(n) operation, where n is Count. If the item is not found, it will return -1
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