iterator

问题 Suppose I am writing a function foo: Iterator[A] => Iterator[List[A]] to transform a given iterator into an iterator of chunks of duplicates : def foo[T](it: Iterator[A]): Iterator[List[A]] = ??? foo("abbbcbbe".iterator).toList.map(_.mkString) // List("a", "bbb", "c", "bb", "e") In order to implement foo I want to reuse function splitDupes: Iterator[A] => (List[A], Iterator[A]) that splits an iterator into a prefix with duplicates and the rest (thanks a lot to Kolmar who suggested it here)

问题 Suppose I am writing a function foo: Iterator[A] => Iterator[List[A]] to transform a given iterator into an iterator of chunks of duplicates : def foo[T](it: Iterator[A]): Iterator[List[A]] = ??? foo("abbbcbbe".iterator).toList.map(_.mkString) // List("a", "bbb", "c", "bb", "e") In order to implement foo I want to reuse function splitDupes: Iterator[A] => (List[A], Iterator[A]) that splits an iterator into a prefix with duplicates and the rest (thanks a lot to Kolmar who suggested it here)

问题 I have a struct containing a 2D array: struct Block; struct World { blocks: [[Block; 10]; 10], } How could I write a function which returns an iterator over a 2D array, but with the enumeration indices included? fn enumerate_blocks(&self) -> impl Iterator<Item = (usize, usize, &Block)> I managed to write an implementation of the function which just returns an iterator without enumeration indices: fn blocks(&self) -> impl Iterator<Item = &Block> { self.blocks.iter().flat_map(|x| x.iter()) } If

问题 I have a struct containing a 2D array: struct Block; struct World { blocks: [[Block; 10]; 10], } How could I write a function which returns an iterator over a 2D array, but with the enumeration indices included? fn enumerate_blocks(&self) -> impl Iterator<Item = (usize, usize, &Block)> I managed to write an implementation of the function which just returns an iterator without enumeration indices: fn blocks(&self) -> impl Iterator<Item = &Block> { self.blocks.iter().flat_map(|x| x.iter()) } If

问题 I want to pass Iterators to a function, which then computes some value from these iterators. I am not sure how a robust signature to such a function would look like. Lets say I want to iterate f64. You can find the code in the playground: https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=c614429c541f337adb102c14518cf39e My first attempt was fn dot(a : impl std::iter::Iterator<Item = f64>,b : impl std::iter::Iterator<Item = f64>) -> f64 { a.zip(b).map(|(x,y)| x*y).sum() }

问题 I'm struggling to turn a simple recursive function into a simple iterator. The problem is that the recursive function maintains state in its local variables and call stack -- and to turn this into a rust iterator means basically externalizing all the function state into mutable properties on some custom iterator struct. It's quite a messy endeavor. In a language like javascript or python, yield comes to the rescue. Are there any techniques in Rust to help manage this complexity? Simple

问题 I'm struggling to turn a simple recursive function into a simple iterator. The problem is that the recursive function maintains state in its local variables and call stack -- and to turn this into a rust iterator means basically externalizing all the function state into mutable properties on some custom iterator struct. It's quite a messy endeavor. In a language like javascript or python, yield comes to the rescue. Are there any techniques in Rust to help manage this complexity? Simple

问题 Is there a way I could convert the xy_mean function to be computed using the pandas library just like the y_mean function. I found out that the pandas function Y_mean = pd.Series(PC_list).rolling(number).mean().dropna().to_numpy() is way faster than the numpy version ym = (np.convolve(PC_list, np.ones(shape=(number)), mode='valid')/number)[:-1] . The equation for the xy_mean would be ((index of value)*value + (index of value)*value)/number The index number would be dependent on the variable

问题 I was reading Constructing a vector with istream_iterators which is about reading a complete file contents into a vector of chars. While I want a portion of a file to be loaded in to a vector of chars. #include <iostream> #include <fstream> #include <iterator> #include <vector> #include <algorithm> using namespace std; int main(int argc, char *argv[]) { ifstream ifs(argv[1], ios::binary); istreambuf_iterator<char> beginItr(ifs); istreambuf_iterator<char> endItr(beginItr); advance(endItr, 4);

问题 I am trying to iterate over three data frames to find the difference between them. I have a master data frame which contains everything and two other data frames which contains partial of master data frame. I am trying to write a python code to identify what is missing in the other two files. Master file looks like following: ID Name 1 Mike 2 Dani 3 Scott 4 Josh 5 Nate 6 Sandy second data frame looks like following: ID Name 1 Mike 2 Dani 3 Scott 6 Sandy Third data frame looks like following: