indexing

问题 Provided is a list of data about a store’s inventory where each item in the list represents the name of an item, how much is in stock, and how much it costs. Print out each item in the list with the same formatting, using the .format method (not string concatenation). For example, the first print statement should read The store has 12 shoes, each for 29.99 USD. I initialized an index variable, i, to 0 and wrote for loop with a loop variable to go through the contents in the list. I then have

问题 I am using Lucene 8.2.0 in Java 11. I am trying to index a Long value so that I can filter by it using a range query, for example like so: +my_range_field:[1 TO 200] . However, any variant of that, even my_range_field:[* TO *] , returns 0 results in this minimal example. As soon as I remove the + from it to make it an OR , I get 2 results. So I am thinking I must make a mistake in how I index it, but I can't make out what it might be. From the LongPoint JavaDoc: An indexed long field for fast

问题 I have a dataframe that has dates, assets, and then price/volume data. I'm trying to pull in data from 7 days ago, but the issue is that I can't use shift() because my table has missing dates in it. date cusip price price_7daysago 1/1/2017 a 1 1/1/2017 b 2 1/2/2017 a 1.2 1/2/2017 b 2.3 1/8/2017 a 1.1 1 1/8/2017 b 2.2 2 I've tried creating a lambda function to try to use loc and timedelta to create this shifting, but I was only able to output empty numpy arrays: def row_delta(x, df, days,

问题 This may be worded incorrectly because I'm a wee beginner, but if I have a string how to I find a certain characters index like you can with the .index thing in lists. With a list it makes sense: l = ["cat", "dog", "mouse"] animal = l.index["dog"] will return [1], but how do I do the same thing with strings . . . s = "mouse" animal_letter = s.index["s"] it says there is no attribute .index Is there another way I can do this? 回答1: Try the string.find method. s = "mouse" animal_letter = s.find(

问题 This may be worded incorrectly because I'm a wee beginner, but if I have a string how to I find a certain characters index like you can with the .index thing in lists. With a list it makes sense: l = ["cat", "dog", "mouse"] animal = l.index["dog"] will return [1], but how do I do the same thing with strings . . . s = "mouse" animal_letter = s.index["s"] it says there is no attribute .index Is there another way I can do this? 回答1: Try the string.find method. s = "mouse" animal_letter = s.find(

问题 Cassandra uses LSM tree for storage, but what exactly is the index structure of cassandra ? For e.g Both Mongo and Couchbase use BTree. 回答1: It depends on the version of Cassandra you are actually using. For version prior to 3.4 indexes are implemented as hidden Cassandra tables holding the key value of the data you wish to access. Main disadvantage of this strategy is that since SStables are subjected to compactions, you cannot reference data directly, instead you are given a key, and you

问题 Cassandra uses LSM tree for storage, but what exactly is the index structure of cassandra ? For e.g Both Mongo and Couchbase use BTree. 回答1: It depends on the version of Cassandra you are actually using. For version prior to 3.4 indexes are implemented as hidden Cassandra tables holding the key value of the data you wish to access. Main disadvantage of this strategy is that since SStables are subjected to compactions, you cannot reference data directly, instead you are given a key, and you

问题 I'M trying to create a text index without a default language. The official docs specify If you specify a language value of "none", then the text search uses simple tokenization with no list of stop words and no stemming. Hence I tried: createIndex({aliases : "text"}, {name : "aliases_txt"}, {default_language: "none"}) However the created index ignores my option and has "english" as default language: { "v": 1, "key": { "_fts": "text", "_ftsx": 1 }, "name": "aliases_txt", "ns": "ner-dict.ents",

问题 I'M trying to create a text index without a default language. The official docs specify If you specify a language value of "none", then the text search uses simple tokenization with no list of stop words and no stemming. Hence I tried: createIndex({aliases : "text"}, {name : "aliases_txt"}, {default_language: "none"}) However the created index ignores my option and has "english" as default language: { "v": 1, "key": { "_fts": "text", "_ftsx": 1 }, "name": "aliases_txt", "ns": "ner-dict.ents",

问题 We have a social app where users can chat with each other and we’ve reached 350K messages! We recently noticed that as the number of messages is growing, the find operations are getting slower! I believe the issue here is that the Message collection is not indexed. That’s what I want to do now! I found this piece of code at the MongoDB docs: db.comments.ensure_index(('discussion_id', 1)) This is my Message collection: { chatRoom: <Pointer>, user: <Pointer>, text: <String>, isSeen: <Bool> } So