Amon | yet another web application framework | Web Framework library

You write

You can get the ids like so

You can use includes to check if something exists in the array or not.

You can use filter with includes like this.

It looks like you create a single node in your getNames() method. For each insertion, you will need to create a new node, fill in that node, and then add it to the linked list, which will need to be in a loop of its own (your current loop just looks for the end of the linked list). Plus, because you initialize the head of the linked list to NULL, you never enter your loop to begin with when you perform the test if(head != NULL). This can be accomplished with something like:

You cshould use a subquery for max mac group by name and join this to you original table

Ok I got this to work, and want to step through a few things with you.

First why you were getting the error message "Property or Indexer “Output0Buffer.ChangeType“ cannot be assigned to -- it is read only". The reason you were getting this is that you had every attribute on your Output 0 buffer set to "text stream [DT_TEXT]". This is a blob data type, equivalent to varchar(max) or Text in SQL Server, and cannot simply be assigned using a "=". In order to do this in code you have to do this (example for Change_Type):

We will add our list's elements to the set and because of set stores unique elements, set's length will give us unique element count of our list.

But there is a problem. Set store values via hashing and because of lists are mutable and doesn't have hash so i need to convert it to a tuple (tuples are immutable!).

There is a little more to a proper intersection via st_intersects(or st_crop) than just subsetting a bunch of coordinates. Below you will find a working solution for your example that is trying to answer both of your questions.

For question 1 I would suggest that identifying the polygons that intersect with the bbox before cropping them can in many cases speed up things quite a bit, especially if you have many polygons and the area of the bbox is small compared to the extent of the polygons area.

Regarding question 2, you can use package sfheaders which provides methods to create sf objects from data.frames/data.tables etc.

Finally, I reshaped the timing code a little to better reflect what each of the steps need to do to provide similar output, thus making the comparison a lot fairer.

The final result of the data.table way of things is different from the st_crop as this approach only subsets coordinates to those inside the bbox, but does not insert the coordinates of the bbox at the appropriate position. This operation is likely costly, as we need to identify these correct positions. Therefore, you will get arbitrary shapes in the result, and thing may even break as you may likely produce invalid geometries.

In general, I'd stick with the st_crop approach which will likely save you trouble later on. If your area of interest is big, has many polygons and the bbox you use is small in relation to the overall area, I expect that identifying the polygons that intersect with the bbox before doing the actual intersection will speed up things quite a bit.

i tried a solution like: