Question

我一直在舔我的脚趾到Rcpp，以加快我目前在R中执行的一些操作。我遇到的一个问题是修改通过引用函数传递的NumericVector。

特别是，下面的函数似乎不会改变传递给函数的NumericVector（x）：

import {Component, forwardRef, Input, ViewChild, KeyValueDiffers} from '@angular/core';
import {
  ControlValueAccessor, NG_VALUE_ACCESSOR, FormControl, NgModel,
  NG_ASYNC_VALIDATORS
} from '@angular/forms';
import {Observable} from "rxjs/Rx";

@Component({
  selector: 'input-email',
  templateUrl: './email.component.html',
  styleUrls: ['./email.component.css'],
  providers: [
    { provide: NG_VALUE_ACCESSOR, useExisting: forwardRef(() => InputEmailComponent), multi: true },
    { provide: NG_ASYNC_VALIDATORS, useExisting: forwardRef(() => InputEmailComponent), multi: true }
  ]
})
export class InputEmailComponent implements ControlValueAccessor {


  value:String = null;
  differ: any;

  @ViewChild('f') f:NgModel;

  @Input()
  info:String = "Email";

  @Input()
  placeholder:String = "Email";

  propagateChange:any = (val) => {};

  constructor(private differs: KeyValueDiffers) {
    this.differ = differs.find({}).create(null);
  }

  onChange(){
    this.propagateChange(this.value);
  }

  /**
   * Write a passed NgValue value to the element.
   */
  writeValue(value) {
    if (value && this.value != value) {
      this.value = value;
      //setTimeout(()=>{this.propagateChange(this.value);},0)
    }
  }

  /**
   * Set the function to be called
   * when the control receives a change event.
   * registers 'fn' that will be fired when changes are made
   * this is how we emit the changes back to the form
   */
  registerOnChange(fn) {
    this.propagateChange = fn;
  }

  /**
   * Set the function to be called
   * when the control receives a touch event.
   */
  registerOnTouched(fn) {}


  /**
   * Set the function to be called
   * to validate if input has errors.
   */
  validate(c: FormControl):any {

    return new Promise((resolve, reject) => {
      Observable.of(c)
        .debounceTime(300)
        .switchMap(val => {
            return Observable.of(val.errors);
        })
        .subscribe(result => {
          console.log('RESOLVING ASYNC VALIDATOR: ' + JSON.stringify(result, null, 2));
          resolve(result);
        });
    });

  }
}

另一方面，下面的代码确实：

void f1(NumericVector &x){
  NumericVector y(1);
  y[0] = 1;
  x = y;
}

基于此，似乎您无法通过为其指定另一个NumericVector来修改通过引用函数传递的NumericVector。相反，你必须逐个元素地修改它。这是对的吗？

这不一定是一个问题，但似乎第一个函数应该起作用，所以我不想不必要地遍历向量的每个元素。

rcpp通过引用传递向量

0 个答案: