slice | 易学教程

golang学习笔记 ---- array/slice/maps

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array package main import "fmt" func main() { // 这里我们创建了一个数组 `a` 来存放刚好 5 个 `int`。 // 元素的类型和长度都是数组类型的一部分。数组默认是 // 零值的，对于 `int` 数组来说也就是 `0`。 var a [5]int fmt.Println("emp:", a) // 我们可以使用 `array[index] = value` 语法来设置数组 // 指定位置的值，或者用 `array[index]` 得到值。 a[4] = 100 fmt.Println("set:", a) fmt.Println("get:", a[4]) // 使用内置函数 `len` 返回数组的长度。 fmt.Println("len:", len(a)) // 使用这个语法在一行内声明并初始化一个数组。 b := [5]int{1, 2, 3, 4, 5} fmt.Println("dcl:", b) // 数组类型是一维的，但是你可以组合 // 构造多维的数据结构。 var twoD [2][3]int for i := 0; i < 2; i++ { for j := 0; j < 3; j++ { twoD[i][j] = i + j } } fmt.Println("2d: ", twoD) } 在使用 fmt

non continuous index slicing on tensor object in tensorflow (Advanced indexing like numpy)

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问题 I have looked at different ways of slicing in tensorflow, namely, tf.gather and tf.gather_nd . In tf.gather, it just slices over a dimension, and also in tf.gather_nd it just accepts one indices to be applied over the input tensor. What I need is different, I want to slice over the input tensor using two different tensor;one slices over the rows the second slices over the column and they are not in the same shape necessarily. For example: suppose this is my input tensor in which I want to

Parser in Ruby: #slice! inside #each_with_index = missing element

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问题 Let's say, I want to separate certain combinations of elements from an array. For example data = %w{ start before rgb 255 255 255 between hex FFFFFF after end } rgb, hex = [], [] data.each_with_index do |v,i| p [i,v] case v.downcase when 'rgb' then rgb = data.slice! i,4 when 'hex' then hex = data.slice! i,2 end end pp [rgb, hex, data] # >> [0, "start"] # >> [1, "before"] # >> [2, "rgb"] # >> [3, "hex"] # >> [4, "end"] # >> [["rgb", "255", "255", "255"], # >> ["hex", "FFFFFF"], # >> ["start",

Pandas: slice one multiindex dataframe with multiindex of another when some levels don't match

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问题 I have two multiindexed dataframes, one with two levels and one with three. The first two levels match in both dataframes. I would like to find all values from the first dataframe where the first two index levels match in the second dataframe. The second data frame does not have a third level. The closest answer I have found is this: How to slice one MultiIndex DataFrame with the MultiIndex of another -- however the setup is slightly different and doesn't seem to translate to this case.

Pandas: slice one multiindex dataframe with multiindex of another when some levels don't match

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In a Pandas dataframe, how can I extract the difference between the values on separate rows within the same column, conditional on a second column? [duplicate]

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问题 This question already has an answer here : Pandas groupby diff (1 answer) Closed last year . This is part of a larger project, but I've broken my problem down into steps, so here's the first step. Take a Pandas dataframe, like this: index | user time --------------------- 0 F 0 1 T 0 2 T 0 3 T 1 4 B 1 5 K 2 6 J 2 7 T 3 8 J 4 9 B 4 For each unique user, can I extract the difference between the values in column "time," but with some conditions? So, for example, there are two instances of user J

getitem with slices on a list of lists

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问题 I'm creating a class representing a list of lists. __getitem__ is giving me headaches. Everything goes swimmingly until I introduce slices as parameters. Demonstration code # Python version 2.7.5 class NestedLists: _Cells = [['.', '.', '.', '.', '.'], ['.', '.', 'N', '.', '.'], ['.', 'C', 'A', 'T', '.'], ['.', '.', 'P', '.', '.'], ['.', '.', '.', '.', '.']] def __getitem__(self, index): if isinstance(index, int): return self._Cells[index] elif isinstance(index, slice): return self._Cells

getitem with slices on a list of lists

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Array.slice on array with one element

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问题 I'm really confused by this. If I do something like this: [1].slice(1) it returns an empty array (in the chrome interactive console). But if I compare: [1].slice(1) === [] it's always false. So my Question is, what does [1].slice(1) really return? 回答1: === compares objects by references. You're comparing two different array objects which are both empty. If you want to check whether an array is empty, check whether .length === 0 . 回答2: That's not a problem of slice or === . If you do [1]==[1]

jquery .each() loop continue on load more button?

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问题 I've made jQuery each loop for my array, but i want to load 6 items on first initiate, then when i click load more button, it will show 7 till 13, and so on. I've done the 6 limitation at first with .slice(), but always failed on load more button, can someone help? my code: function loadName(){ $.getJSON('/namedatabase.php', function(data) { $.each($(data).slice(0, 6),function(i,item){ $(".nameData").append('<div>'+item.name+'</div>'); }); }); } load more button <button class="btn btn-primary