如何使用 ifelse() 命令在 R 中创建虚拟变量 [英] How to create a dummy variable in R using ifelse() command

问题描述

我正在尝试为 R 创建一个虚拟变量.问题是我的餐厅类型"数据集下有许多分类变量.其中，我希望素食餐厅的值为 1，其余为 0.因此，当我运行回归摘要时，我得到了截距，b1 为 review_number，b2 为素食餐厅.例如，非素食餐厅将是 y=b0+b1(reviews_number)，而素食餐厅将是 y=b0+b1(reviews_number)+b2(Vegan).提示是使用 ifelse() 命令，但我似乎不能将系数简化为 3.否则，我需要为每种类型的餐厅分别创建一个值......

I am trying to create a dummy variable for R. The thing is there are many categorical variables under my dataset of restaurants 'type'. Among them, I want Vegan restaurants to have value 1 and the rest to be 0. So when I run summary of the regression, I get the intercept, and b1 as reviews_number and b2 as vegan restaurants. For example, a non-vegan restaurant would be y=b0+b1(reviews_number) and a vegan restaurant will be y=b0+b1(reviews_number)+b2(Vegan). The hint is to use ifelse()command, but I can't seem to simplify the coefficients to just 3. Or else, I need to create a value for each type of restaurant respectively......

推荐答案

假设您的数据框名为 df，您可以使用以下方法创建虚拟变量 (Vegan):

Assuming your data frame is called df, you can create your dummy variable (Vegan) using:

df$Vegan <- ifelse(df$type == "Vegan", 1, 0) # where variable type is type of restaurants 

但是，您应该注意，如果 type 是存储为因子，您还可以使用 y=b0+ 获得每种类型餐厅的系数(与参考水平相比)b1(reviews_number)+b2(type) 即 y~reviews+type，如@mlt 所指.

However, you should note that if type is a stored as factor, you can also get the coefficient on each type of restaurants (compared to the reference level) using y=b0+b1(reviews_number)+b2(type) i.e. y~reviews+type, as pointed by @mlt.

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