numpy数组与布尔数组_数组和布尔

迷南。 2023-02-21 15:26 81阅读 0赞

numpy数组与布尔数组

One of the annoyances of old-school JavaScript was side effects; then `Array.prototype` got methods like `filter`, `map`, and `forEach` so we didn't need to burn variables before looping over values.  I can't explain how happy I am that the JavaScript language continues to evolve.

老式JavaScript的烦恼之一是副作用。 然后`Array.prototype`获得了`filter` ， `map`和`forEach`类的方法，因此我们不需要在遍历值之前刻录变量。 我无法解释JavaScript语言的不断发展让我多么高兴。

Every once in a while I need to filter an array by *not* its original value but instead a new value, so I use `map`:

每过一段时间，我需要进行过滤*而不是*它的原始值的阵列，而是一个新的价值，所以我使用`map` ：

myArray.map(item => {
        // Do whatever processing...
    
        // If we don't care about the item, return false or null or undefined
        return false;
    });

While I get the new values I want, sometimes if an iteration returns a result I don't want, I return null or false, which is great, but then I'm left with a bunch of useless items in the resulting array.  The next step is using filter, in which case I could do:

当我获得所需的新值时，有时如果迭代返回了我不想要的结果，我将返回null或false，这很好，但是随后在结果数组中留下了一堆无用的项。 下一步是使用过滤器，在这种情况下，我可以这样做：

myArray
        .map(item => {
            // ...
        })
        // Get rid of bad values
        .filter(item => item);

Since the values I don't want aren't truthy, the filter above removes those bad items.  Did you know there's a clearer way with `Boolean`?

由于我不想要的值不真实，因此上面的过滤器删除了这些不良项。 您是否知道`Boolean`有更清晰的方法？

myArray
        .map(item => {
            // ...
        })
        // Get rid of bad values
        .filter(Boolean);

If the value isn't truthy the item is filtered out and I'm left with only the items I want!

如果值不正确，该项目将被过滤掉，而我只剩下我想要的项目！

> 翻译自: [https://davidwalsh.name/array-boolean][https_davidwalsh.name_array-boolean]

numpy数组与布尔数组

[https_davidwalsh.name_array-boolean]: https://davidwalsh.name/array-boolean