tuples

问题 I'm writing some code in F# and I need to multiply and add each element in list of tuples (c,d) by a tuple (a,b) . To clarify, I have some tuple (a,b) And some list of tuples [(c,d),(e,f),(g,h)...] and I'm trying to get [(a*c,b*d),(a*e,b*f),(a*g,b*h)...] and I'm trying to get (with a separate function) [(a+c,b+d),...] I have tried to use List.map to multiply each element in the list by a tuple but I get an error that * is an invalid operator for type tuple. This is how I ended up implementing

问题 How to extract a list of different values from following list of tuples? tuple = ((("test", 123), ("test", 465), ("test", 8910), ("test2", 123))) I want to get a list like: different_values = ("test", "test2") Now I want to access all values by this "keys" and get them by a list: test_values = (123, 456, 8910) test2_values = (123) How to do that? 回答1: I'd transform your data to a dictionary of lists: d = {} for k, v in tuples: d.setdefault(k, []).append(v) Now you can access the keys as d

问题 I need to write a 2D numpy array to a file, including its dimensions so I can read it from a C++ program and create the corresponding array. I have written some simple code that saves the array and it can be read from C++, but if I try to write the array's size first it always gives me an error. Here's my simple python code: 1 file = open("V.bin","wb") 2 file.write(V.shape) 3 file.write(V) 4 file.close() The second line gives the error, I've also tried: n1, n2 = V.shape file.write(n1) file

问题 This question already has an answer here : Why aren't the entries in a Kotlin Pair mutable? (1 answer) Closed 2 years ago . Why can't I change the values in the pair: var p: Pair<Int, String> = Pair(5, "Test") p.first = 3 Error under p.first : Val cannot be reassigned 回答1: Pair, like most data classes, is immutable. Its definition is effectively data class Pair<out A, out B>(val first: A, val second: B) If it were mutable, it could not be covariant in out A and out B , nor would it be safe to

问题 This question already has an answer here : Why aren't the entries in a Kotlin Pair mutable? (1 answer) Closed 2 years ago . Why can't I change the values in the pair: var p: Pair<Int, String> = Pair(5, "Test") p.first = 3 Error under p.first : Val cannot be reassigned 回答1: Pair, like most data classes, is immutable. Its definition is effectively data class Pair<out A, out B>(val first: A, val second: B) If it were mutable, it could not be covariant in out A and out B , nor would it be safe to

问题 This question already has an answer here : Why aren't the entries in a Kotlin Pair mutable? (1 answer) Closed 2 years ago . Why can't I change the values in the pair: var p: Pair<Int, String> = Pair(5, "Test") p.first = 3 Error under p.first : Val cannot be reassigned 回答1: Pair, like most data classes, is immutable. Its definition is effectively data class Pair<out A, out B>(val first: A, val second: B) If it were mutable, it could not be covariant in out A and out B , nor would it be safe to

问题 Edit originally the question was "Collection to Tuple" as I assumed I needed a tuple in order to do variable multi-assignment. It turns out that one can do variable multi-assignment directly on collections. Retitled the question accordingly. Original Have a simple Seq[String] derived from a regex that I would like to convert to a Tuple. What's the most direct way to do so? I currently have: val(clazz, date) = captures match { case x: Seq[String] => (x(0), x(1)) } Which is ok, but my routing

问题 i am trying to access to a field within a Tuple2 and compiler is returning me an error. The software tries to push a case class within a kafka topic, then i want to recover it using spark streaming so i can feed a machine learning algorithm and save results within a mongo instance. Solved! I finally solved my problem, i am going to post the final solution: This is the github project: https://github.com/alonsoir/awesome-recommendation-engine/tree/develop build.sbt name := "my-recommendation

问题 So I am trying to do this: tuple([1]) The output I expect is : (1) However, I got this: (1,) But if I do this: tuple([1,2]) It works perfectly! like this: (1,2) This is so weird that I don't know why the tuple function cause this result. Please help me to fix it. 回答1: This is such a common question that the Python Wiki has a page dedicated to it: One Element Tuples One-element tuples look like: 1, The essential element here is the trailing comma. As for any expression, parentheses are

问题 I've been trying to figure out how to make these tuples index keys in pandas but I'm getting an error. How can I use the suggestion from the error with pd.Categorical below to fix this error? I am aware that I can convert to a string but I am curious to see what is meant by the suggestion in the error message? This works perfectly fine when I run it with 0.22.0 . I've opened a GitHub issue for this if anyone wants to see the proper output from 0.22.0 . I want to update my pandas and handle