I have structure which is big in memory. It is TList; each item is TMyObject and TMyObject holds Data field which is record (with n fields: integer, boolean). List may have 1.000.000 items.
I want to make list compact: I want to have list not of TMyObject but list of record, each list item must be record. So no proxy TMyObjects are made. Records are saved in list as is.
How to do this "list class" w/o making new big code, w/o making my own Insert/Delete/Add, w/o reallocating records in Insert/Delete/Add?
(using FPC 3.0, Lazarus)
There are a few options but I suspect the most appropriate would be TFPGList<T>.
Related
I have a model called lists, which has a column called item_ids. item_ids is a JSON column (MySQL) and the column contains array of UUIDs, each referring to one item.
Now when someone creates a new list, I need to search whether there is an existing list with same set of UUIDs, and I want to do this search using query itself for faster response. Also use ActiveRecord querying as much as possible.
How do i achieve this?
item_ids = ["11E85378-CFE8-39F8-89DC-7086913CFD4B", "11E85354-304C-0664-9E81-0A281BE2CA42"]
v = List.new(item_ids: item_ids)
v.save!
Now, how do I check whether a list exists which has item ids exactly matches with that mentioned in query ? Following wont work.
list_count = List.where(item_ids: item_ids).count
Edit 1
List.where("JSON_CONTAINS(item_ids, ?) ", item_ids.to_json).count
This statement works, but it counts even if only one of the item matches. Looking for exact number of items.
Edit 2
List.where("JSON_CONTAINS( item_ids, ?) and JSON_LENGTH(item_ids) = ?", item_ids.to_json, item_ids.size).count
Looks like this is working
You can implement a has many relation between lists and items and then access like this.
List.includes(:item).where('items.id in (?)',item_ids)
To implement has_many relation:
http://guides.rubyonrails.org/association_basics.html#the-has-many-through-association
I know how to parse json cells in Open refine, but this one is too tricky for me.
I've used an API to extract the calendar of 4730 AirBNB's rooms, identified by their IDs.
Here is an example of one Json file : https://fr.airbnb.com/api/v2/calendar_months?key=d306zoyjsyarp7ifhu67rjxn52tv0t20¤cy=EUR&locale=fr&listing_id=4212133&month=11&year=2016&count=12&_format=with_conditions
For each ID and each day of the year from now until november 2017, i would like to extract the availability of this rooms (true or false) and its price at this day.
I can't figure out how to parse out these informations. I guess that it implies a series of nested forEach, but i can't find the right way to do this with Open Refine.
I've tried, of course,
forEach(value.parseJson().calendar_months, e, e.days)
The result is an array of arrays of dictionnaries that disrupts me.
Any help would be appreciate. If the operation is too difficult in Open Refine, a solution with R (or Python) would also be fine for me.
Rather than just creating your Project as text, and working with GREL to parse out...
The best way is just select the JSON record part that you want to work with using our visual importer wizard for JSON files and XML files (you can even use a URL pointing to a JSON file as in your example). (A video tutorial shows how here: https://www.youtube.com/watch?v=vUxdB-nl0Bw )
Select the JSON part that contains your records that you want to parse and work with (this can be any repeating part, just select one of them and OpenRefine will extract all the rest)
Limit the amount of data rows that you want to load in during creation, or leave default of all rows.
Click Create Project and now your in Rows mode. However if you think that Records mode might be better suited for context, just import the project again as JSON and then select the next outside area of the content, perhaps a larger array that contains a key field, etc. In the example, the key field would probably be the Date, and why I highlight the whole record for a given date. This way OpenRefine will have Keys for each record and Records mode lets you work with them better than Row mode.
Feel free to take this example and make it better and even more helpful for all , add it to our Wiki section on How to Use
I think you are on the right track. The output of:
forEach(value.parseJson().calendar_months, e, e.days)
is hard to read because OpenRefine and JSON both use square brackets to indicate arrays. What you are getting from this expression is an OR array containing twelve items (one for each month of the year). The items in the OR array are JSON - each one an array of days in the month.
To keep the steps manageable I'd suggest tackling it like this:
First use
forEach(value.parseJson().calendar_months,m,m.days).join("|")
You have to use 'join' because OR can't store OR arrays directly in a cell - it has to be a string.
Then use "Edit Cells->Split multi-valued cells" - this will get you 12 rows per ID, each containing a JSON expression. Now for each ID you have 12 rows in OR
Then use:
forEach(value.parseJson(),d,d).join("|")
This splits the JSON down into the individual days
Then use "Edit Cells->Split multi-valued cells" again to split the details for each day into its own cell.
Using the JSON from example URL above - this gives me 441 rows for the single ID - each contains the JSON describing the availability & price for a single day. At this point you can use the 'fill down' function on the ID column to fill in the ID for each of the rows.
You've now got some pretty easy JSON in each cell - so you can extract availability using
value.parseJson().available
etc.
I have a nested repeated structure, the repeated structure is of variable length. For example, it could be a person object with a repeated structure that holds cities the person has lived in. I'd like to find the last item in that list say to find current city person lives in. Is there an easy way to do this, I tried looking around jsonpath functions but I'm not sure how to use it with "within". Any help please?
1) You can use LAST and WITHIN
SELECT
FIRST(cell.value) within record ,
LAST(cell.value) within record
FROM [publicdata:samples.trigrams]
where ngram = "! ! That"
2) or if you want something more advanced you can use POSITION
POSITION(field) - Returns the one-based, sequential position of field within a set of repeated fields.
You can check the samples from trigrams (click on Details to see the unflatten schema)
https://bigquery.cloud.google.com/table/publicdata:samples.trigrams?pli=1
And when you run POSITION, you get the ordering of that field.
SELECT
ngram,
cell.value,
position(cell.volume_count) as pos,
FROM [publicdata:samples.trigrams]
where ngram = "! ! That"
Now that you have the position, you can query for last one.
I've created a flash AS3 user form for sales people. When I create a user, I select multiple cities from a list component and drop them into an array. When added to the mySQL DB these entries are kept in a separte table which I can then call upon at any time using XML to bring them back into AS3. Now I'm using the same form as a user updaete form and populating it with data from previous MySQL insert.
My question is - How could I have these cities show as 'selected' on the list Component when the update form is loaded? Thus allowing the someone to add to or substract from that selection set. I'm trying to set selectedItems to match the ID's in the XML but failing miserably.
as a test I tried
addUser.citiesList.selectedItems = [3,4];
addUser.citiesList.selectedIndices = [3,4];
The selectedItems yield nothing but the selectedIndices works but I don't want to start matching indexes with Item ID's
looked all over but can't seem to find an answer. Am I missing something or is this not possible?
Well I finally got it working.
Having got the data out of the MySQL db, through PHP and into Flash as XML, I then pushed the user city values into a userCity array.
I got the AS3 list component in the form populated in the same way with all the cities.
I then used the userCity array in a nested for loop to inerate through all the cities in the list component, picking out the ones that had been previously selected and grabbing the index of each to pop into a new array which was the array used for the 'selectedindicies' and hey presto. I now have a cities list (about 36 cities) with the previously selected cities (about 5 cities) already selected and highlighted so that the user knows which cities the sales peson already manages. Now they can add or subtract from that and it will be picked up by my on change event as normal.
The Adobe resources on selectedIndices and selectedItems, for someone like me, who's learning is to say the least - pittyful...
I hope this helps someone else out...
I've got records in my MySQL projects database that have several boolean flags to help me sort the data. I have 3 categories planning, landscape, and environmental and 4 classes (or subcategories) for each category; industrial, government, education, residential.
My goal is to use ColdFusion to create and store the project_id numbers in an array of some kind that will basically have the projects sorted by category and class. That way I can grab just the industrial projects in the planning category and construct a link to that project.
So, the first position in the array would be planning and inside that first position would be the 4 classes, then, within that would be all of the project_id numbers that returned true for those particular criteria.
The logic I'm looking to create goes like this...
Loop over the query result, if planning = true and industrial = true, place the project id # into the planning array inside the industrial array.
How can I use <cfloop> to loop over the list of project records, recognize the category and class flags and construct a clean and usable dataset? Can this be handles in the query in some way?
Figure out the desired data structure
look at your existing data structure
figure out the algorithm to translate from one to the other
You may cfloop the query, and use a large cfswitch (or large set of if-then-else) to figure out how you want to store the id in your desired data structure. Or if you can map the class/category name as a struct key, then it might be easier.
Or you may use cfoutput group="" if it helps (cfloop group="" is available on in CF10+)
Finally, maybe you don't even need the data structure, just use Query of Queries wherever you need.
You may be able to utilize the Underscore.cfc library for this. For example, you could use the filter function to extract an array of structs representing the query rows you want:
planningArray = _.filter(queryResult, function(row){
return (row.planning == true && row.industrial == true);
});