map-function

JavaScript “map” Function

由 拈花ヽ惹草 提交于 2019-12-11 05:07:30
问题 Looking at the map function in JavaScript, what am I doing wrong here? // input: [{name: "Kevin"}, {name: "Bob"}]; // output: [{"Kevin" : 0}, {"Bob" : 1}]; var map = function(arr, property) { var i = 0; var m = arr.prototype.map(makeKv); // input: {name: "Kevin"} // output: {"Kevin" = i} // GLOBAL function makeKv(item) { return {item: i++}; }; console.log("m : " + m); } http://jsfiddle.net/FgdSj/2 Also, if you could help please me get rid of the global too. 回答1: There are a few issues here:

Apache Spark Function2, not getting declaration right

由 寵の児 提交于 2019-12-11 04:26:04
问题 (This is based on trying to map a Integer RDD to a TholdDropResult RDD, but we need to initialize a single SparkDoDrop to generate all the (10^8) TholdDropResults, hence the use of mapPartitionsWithIndex, the only flavor in Java of mapPartition that will provide the type of function we need, methinks.) Question: I am getting an error using org.apache.spark.api.java.function.Function2 I am not able to figure out how to work the "boolean" into a new Function2 When I try this code, scroll right

Passing values to a map function - CouchDB

由 依然范特西╮ 提交于 2019-12-11 02:34:00
问题 I was wondering whether its possible to pass values to a map function in couchDB design document. For Example: In the code below is it possible to pass a value that has been entered by the user and use that value to run the map function. Maybe I can pass users UserName when they login and then display the view based on the map function. function(doc) { if(doc.name == data-Entered-By-User) { emit(doc.type, doc); } } Thank you in advance. Regards 回答1: This is a common mistake in CouchDB when

What does duckmap really do?

由 谁说我不能喝 提交于 2019-12-10 02:18:57
问题 From the documentation duckmap will apply &block on each element and return a new list with defined return values of the block. For undefined return values, duckmap will try to descend into the element if that element implements Iterable . But then: my $list = [[1,2,3],[[4,5],6,7]]; say $list.deepmap( *² ); # [[1 4 9] [[16 25] 36 49]] say $list.duckmap( *² ); # [9 9] deepmap behaves pretty much as expected, but I can't really make any sense of what duckmap is doing. This question is related

python map function does not work

由 情到浓时终转凉″ 提交于 2019-12-09 03:58:53
问题 This is the code I edit on an editor and compile on a shell. If I enter the integer 19, when I print out c, it is still ['1','9'] instead of the [1,9] I want. I tried this on the interactive interpreter instead of compiling a python file and it worked. a = raw_input("Please enter a positive number ") c = [] c = list(a) map(int, c) 回答1: You need to reassign the map output to c as it is not in-place >>> a=raw_input("Please enter a positive number ") Please enter a positive number 19 >>> c =

Map over list, except for last list element

由 梦想的初衷 提交于 2019-12-08 19:08:55
问题 How do I best map over all elements of a list, except for the last list element? Say we have a list let l = [1,2,3,4] and want to get [2,3,4,4] . I do have a solution, but it doesn't feel like the "functional" way to do it (in ghci): let l = [1,2,3,4] let len = toIntegral $ length l -- to avoid a type mismatch Integer <-> Int let l1 = zip l [1..] let l2 = map (\(x,y) -> if y < len then (x + 1,y) else (x,y)) l1 let l3 = map (fst) l2 Not very nice...I do hope there is a better way! Since I'm a

Python: map in place [duplicate]

由 风格不统一 提交于 2019-12-06 17:18:23
问题 This question already has answers here : Is there an in-place equivalent to 'map' in python? (4 answers) Closed 3 years ago . I was wondering if there is a way to run map on something. The way map works is it takes an iterable and applies a function to each item in that iterable producing a list. Is there a way to have map modify the iterable object itself? 回答1: A slice assignment is often ok if you need to modify a list in place mylist[:] = map(func, mylist) 回答2: It's simple enough to write:

Julia, run function multiple times, save results in array

由 风流意气都作罢 提交于 2019-12-05 11:02:33
I am building a microsimulation model in Julia. I have built the structure of my function and it runs great for for 1 "person". I'd like to write the script to run 100000+ people through the model and save the results in one location. Eventually I'd like to execute this in parallel. Below I have included a simple working version of the code with dummy probabilities. using Distributions # Microsim function function MicroSim(start_age, stages) stage = 0 age = start_age # Set all trackers to 0 Death_tracker = 0 Disease_tracker = 0 # While loop while stage <= stages age = age #####################

Python 3 map dictionary update method to a list of other dictionaries [duplicate]

由 血红的双手。 提交于 2019-12-05 02:51:23
This question already has an answer here: Getting a map() to return a list in Python 3.x 8 answers In Python 2 I can do the following: >> d = {'a':1} >> extras = [{'b':2}, {'c':4}] >> map(d.update, extras) >> d['c'] >> 4 In Python 3 in get a KeyError : >> d = {'a':1} >> extras = [{'b':2}, {'c':4}] >> map(d.update, extras) >> d['c'] >> KeyError: 'c' I would like to achieve the same behavior in Python 3 as in Python 2. I understand that map in Python 3 will return an iterator (lazy evaluation and whatnot), which has to be iterated for the dictionary to be updated. I had assumed the d['c'] key

What does duckmap really do?

由 点点圈 提交于 2019-12-05 00:55:43
From the documentation duckmap will apply &block on each element and return a new list with defined return values of the block. For undefined return values, duckmap will try to descend into the element if that element implements Iterable . But then: my $list = [[1,2,3],[[4,5],6,7]]; say $list.deepmap( *² ); # [[1 4 9] [[16 25] 36 49]] say $list.duckmap( *² ); # [9 9] deepmap behaves pretty much as expected, but I can't really make any sense of what duckmap is doing. This question is related to this issue in perl6/doc . It can be solved with "They couldn't be more different", but I would like
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