Vector

在这一课，我带你去Vegas逛一逛。你将学习用向量在R里面分析你的赌局结果。在这一课结束后，你将学会在R里面创建向量，给他命名，选择其中的元素，并比较不同的向量。

向量是用于存储数值型、字符型或逻辑型数据的一维数组。

注意：

同一向量中无法混杂不同模式的数据。
执行组合功能的函数c()可用来创建向量。

创建向量

首先创建一个变量叫做vegas吧！

将“Go!” 赋值给vegas:

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Let us focus first!

在R里面, 你可以通过执行组合功能的函数c()来创建向量，用, 来隔开向量中的每一个元素。例如：

numeric_vector <- c(1, 2, 3)
character_vector <- c("a", "b", "c")

创建向量以后，你就可以进行计算啦！

小练习：完成下面的代码，创建boolean_vector包含这三个元素: TRUE, FALSE and TRUE，记得按顺序哈。

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赌城是个藏龙卧虎的地方，没有两把刷子，你小心输到底裤都没有。是时候亮出你的数据分析超能力啦！

在做第一次分析前，你要先把上一个星期所有的输赢赌局都记录下来：

扑克赌局结果（poker_vector）:

On Monday you won $140
Tuesday you lost $50
Wednesday you won $20
Thursday you lost $120
Friday you won $240

轮盘赌（roulette_vector）:

On Monday you lost $24
Tuesday you lost $50
Wednesday you won $100
Thursday you lost $350
Friday you won $10

好，你把这两个赌局的结果放到向量里面吧！

给向量里的元素命名

作为一个数据分析大师，清楚知道每一个数代表什么非常重要。

在上一个练习里，你建了向量记录一前一周的输赢，但是具体哪一个是哪一天的并不清楚。

所以你要给一个向量里面的每一个元素命名，使用names()这个函数，看着下面扑克牌的例子，给轮盘赌向量的元素也添加对应的星期吧吧！

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

一个好的统计学家都是懒懒的。

你可能在上一个练习里已经体会到了，不停打重复的内容是多么的无聊，哪怕是复制黏贴也是浪费生命。

所以呢，我们要把每一周的星期存到一个变量里来简化我们的工作！

来来来，创建days_vector包含 Monday 到Friday:

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

向量计算

漂亮的数据有了，是时候做分析啦

你每一天的纯进账是多少？
你一周共输了多少钱？
你在扑克或者轮盘赌上的输赢情况如何？

在正式分析之前，你做一做下面向量加法的练习（对应位置的元素）：

eyJsYW5ndWFnZSI6InIiLCJzYW1wbGUiOiJBX3ZlY3RvciA8LSBjKDEsIDIsIDMpXG5CX3ZlY3RvciA8LSBjKDQsIDUsIDYpXG5cbiMgVGFrZSB0aGUgc3VtIG9mIEFfdmVjdG9yIGFuZCBCX3ZlY3RvclxudG90YWxfdmVjdG9yIDwtIFxuICBcbiMgUHJpbnQgb3V0IHRvdGFsX3ZlY3RvciIsInNvbHV0aW9uIjoiQV92ZWN0b3IgPC0gYygxLCAyLCAzKVxuQl92ZWN0b3IgPC0gYyg0LCA1LCA2KVxuXG4jIFRha2UgdGhlIHN1bSBvZiBBX3ZlY3RvciBhbmQgQl92ZWN0b3JcbnRvdGFsX3ZlY3RvciA8LSBBX3ZlY3RvciArIEJfdmVjdG9yXG5cbiMgUHJpbnQgb3V0IHRvdGFsX3ZlY3RvclxudG90YWxfdmVjdG9yIn0=

现在可以计算一下你每一个的输赢啦，就是扑克与轮盘赌的每一个的和：

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

我们继续计算：

一周里面扑克的进账情况
一周里面轮盘赌的进账情况
一周里两种赌局的总体输赢

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

好吧，好像输了～

输了就要汲取教训，看看是不是你在某一个游戏里不太在行？比较一下两种赌局的收益就知道啦！是不是你比较擅长扑克？

结果比较

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

根据上面的结果，你是不是要调整自己的策略了？多玩扑克？

向量选子集

看一看你周三的扑克牌，表现怎么样？

这就是要抽取向量里面的元素了。不仅是向量，我们后面的数据框，列表，都可以用方括号[]来提取里面的元素。星期三在第三个位置，所以方括号里放数字3。把这个提取来的元素赋值给 poker_wednesday吧。

eyJsYW5ndWFnZSI6InIiLCJzYW1wbGUiOiIjIFBva2VyIGFuZCByb3VsZXR0ZSB3aW5uaW5ncyBmcm9tIE1vbmRheSB0byBGcmlkYXk6XG5wb2tlcl92ZWN0b3IgPC0gYygxNDAsIC01MCwgMjAsIC0xMjAsIDI0MClcbnJvdWxldHRlX3ZlY3RvciA8LSBjKC0yNCwgLTUwLCAxMDAsIC0zNTAsIDEwKVxuZGF5c192ZWN0b3IgPC0gYyhcIk1vbmRheVwiLCBcIlR1ZXNkYXlcIiwgXCJXZWRuZXNkYXlcIiwgXCJUaHVyc2RheVwiLCBcIkZyaWRheVwiKVxubmFtZXMocG9rZXJfdmVjdG9yKSA8LSBkYXlzX3ZlY3RvclxubmFtZXMocm91bGV0dGVfdmVjdG9yKSA8LSBkYXlzX3ZlY3RvclxuXG4jIERlZmluZSBhIG5ldyB2YXJpYWJsZSBiYXNlZCBvbiBhIHNlbGVjdGlvblxucG9rZXJfd2VkbmVzZGF5IDwtICIsInNvbHV0aW9uIjoiIyBQb2tlciBhbmQgcm91bGV0dGUgd2lubmluZ3MgZnJvbSBNb25kYXkgdG8gRnJpZGF5OlxucG9rZXJfdmVjdG9yIDwtIGMoMTQwLCAtNTAsIDIwLCAtMTIwLCAyNDApXG5yb3VsZXR0ZV92ZWN0b3IgPC0gYygtMjQsIC01MCwgMTAwLCAtMzUwLCAxMClcbmRheXNfdmVjdG9yIDwtIGMoXCJNb25kYXlcIiwgXCJUdWVzZGF5XCIsIFwiV2VkbmVzZGF5XCIsIFwiVGh1cnNkYXlcIiwgXCJGcmlkYXlcIilcbm5hbWVzKHBva2VyX3ZlY3RvcikgPC0gZGF5c192ZWN0b3Jcbm5hbWVzKHJvdWxldHRlX3ZlY3RvcikgPC0gZGF5c192ZWN0b3JcblxuIyBEZWZpbmUgYSBuZXcgdmFyaWFibGUgYmFzZWQgb24gYSBzZWxlY3Rpb25cbnBva2VyX3dlZG5lc2RheSA8LSBwb2tlcl92ZWN0b3JbM10ifQ==

我们继续，看看周二到周四的扑克牌手气如何？我们会用到函数c():

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

如果要取的元素都是临近的，我们可以用:来表示那一段的数：例如上面的例子可以poker_vector[2:4]。现在你来提取周二到周四的轮盘赌的结果，并将其命名为roulette_selection_vector:

eyJsYW5ndWFnZSI6InIiLCJzYW1wbGUiOiIjIFBva2VyIGFuZCByb3VsZXR0ZSB3aW5uaW5ncyBmcm9tIE1vbmRheSB0byBGcmlkYXk6XG5wb2tlcl92ZWN0b3IgPC0gYygxNDAsIC01MCwgMjAsIC0xMjAsIDI0MClcbnJvdWxldHRlX3ZlY3RvciA8LSBjKC0yNCwgLTUwLCAxMDAsIC0zNTAsIDEwKVxuZGF5c192ZWN0b3IgPC0gYyhcIk1vbmRheVwiLCBcIlR1ZXNkYXlcIiwgXCJXZWRuZXNkYXlcIiwgXCJUaHVyc2RheVwiLCBcIkZyaWRheVwiKVxubmFtZXMocG9rZXJfdmVjdG9yKSA8LSBkYXlzX3ZlY3RvclxubmFtZXMocm91bGV0dGVfdmVjdG9yKSA8LSBkYXlzX3ZlY3RvclxuXG4jIERlZmluZSBhIG5ldyB2YXJpYWJsZSBiYXNlZCBvbiBhIHNlbGVjdGlvblxucm91bGV0dGVfc2VsZWN0aW9uX3ZlY3RvciA8LSAiLCJzb2x1dGlvbiI6IiMgUG9rZXIgYW5kIHJvdWxldHRlIHdpbm5pbmdzIGZyb20gTW9uZGF5IHRvIEZyaWRheTpcbnBva2VyX3ZlY3RvciA8LSBjKDE0MCwgLTUwLCAyMCwgLTEyMCwgMjQwKVxucm91bGV0dGVfdmVjdG9yIDwtIGMoLTI0LCAtNTAsIDEwMCwgLTM1MCwgMTApXG5kYXlzX3ZlY3RvciA8LSBjKFwiTW9uZGF5XCIsIFwiVHVlc2RheVwiLCBcIldlZG5lc2RheVwiLCBcIlRodXJzZGF5XCIsIFwiRnJpZGF5XCIpXG5uYW1lcyhwb2tlcl92ZWN0b3IpIDwtIGRheXNfdmVjdG9yXG5uYW1lcyhyb3VsZXR0ZV92ZWN0b3IpIDwtIGRheXNfdmVjdG9yXG5cbiMgRGVmaW5lIGEgbmV3IHZhcmlhYmxlIGJhc2VkIG9uIGEgc2VsZWN0aW9uXG5yb3VsZXR0ZV9zZWxlY3Rpb25fdmVjdG9yIDwtIHJvdWxldHRlX3ZlY3RvclsyOjVdIn0=

提取元素还有一种方法，就是用元素的名称。例如我们要知道扑克牌周一的结果 poker_vector["Monday"]。

现在试一试扑克周一周二周三的结果，赋值为poker_start, 并用mean()计算这三天的平均值：

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

下面来一个更有意思的，我们来做一些比较：

在R里面有这样一些逻辑判断：

< for less than
for greater than
<= for less than or equal to
= for greater than or equal to
== for equal to each other
!= not equal to each other

亲，还记得上一章里6>5返回的结果是 TRUE吗？

在R里面，你可以将向量与单个数字比较哦。

c(4, 5, 6) > 5

FALSE FALSE TRUE

上面是把每一个元素与数字5进行比较，得到一个新的向量，里面是比较的结果。

下面你要检测是否poker_vector里面的每一个元素都比0大？也就是找出哪些天是赢钱的？

将结果存成selection_vector并打印出来：

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知道哪些天赢了钱还不够，还要知道到底每一天赢多少。

之前一个练习，你使用selection_vector <- poker_vector > 0知道了哪些天赢钱，现在你把新得到的向量放到poker_vector[]的方括号里。R知道你想干什么，她只会把selection_vector里TRUE的值返回出来。

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

同样的操作，你试一试轮盘赌吧！

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本章结束！

Introduction to R: Vector

Chris Qi

2018