Question

我尝试使用rpy2从questionr包运行multi.split函数。

这是我的代码

from rpy2 import robjects
from rpy2.robjects.packages import importr

questionr = importr(str('questionr'))

data = ["red/blue", "green", "red/green", "blue/red", "red/blue", "green", "red/green", "blue/red", "red/blue", "green", "red/green", "blue/red", "red/blue", "green", "red/green", "blue/red", "red/blue", "green"]
data_vector = robjects.StrVector(data)
multi_split = questionr.multi_split
data_table = multi_split(data_vector, split_char='/')

在最后一行之后

我收到以下错误：

RRuntimeError: Error in `colnames<-`(`*tmp*`, value = c("c(\"red/blue\",_\"green\",_\"red/green\",_\"blue/red\",_\"red/blue\",_\"green\",_.blue",  : 
 'names' attribute [4] must be the same length as the vector [3]

我认为它与我发送的矢量大小有关，因为如果删除最后一项

data = ["red/blue", "green", "red/green", "blue/red", "red/blue", "green", "red/green", "blue/red", "red/blue", "green", "red/green", "blue/red", "red/blue", "green", "red/green", "blue/red", "red/blue"]

然后运行

data_vector = robjects.StrVector(data)
multi_split = questionr.multi_split
data_table = multi_split(data_vector, split_char='/')

我没有收到任何错误消息。如果我改变＆＃34; split_char＆＃39; var，例如：

data_table = multi_split(data_vector, split_char='.')

我没有收到任何错误消息，无论我发送数组的大小。

我试图直接在R（使用R-Studio）中运行匹配代码，它运行时没有问题。关于如何解决这个问题的任何想法？

Answer 1

这似乎是因为函数multi_split（R包中的multi.split）试图使用与第一个参数（此处为"data_vector"）关联的表达式的字符串表示。

R功能的签名是：

multi.split(var, split.char = "/", mnames = NULL)

和mnames的文档是：

给出生成的变量标题的名称。如果为NULL，则名称为根据原始变量名称和答案计算。

在调用multi_split(data_vector, split_char='/')中，嵌入式R无法看到变量名称，因为这是一个Python调用，而data_vector是一个匿名变量（只有内容，没有变量名称）。

我虽然你可以指定mnames但是你检查过这个不起作用（见下面的评论）。这就是代码似乎所说的：无论是否指定了mnames，都会评估行vname <- deparse(substitute(var))：https://github.com/juba/questionr/blob/9cf09f3ffcd6c8df24182380f12d52b061c221ef/R/table.multi.R#L161

另一种方法是计算R表达式的使用。较旧的帖子应该为此提供必要的位：What object to pass to R from rpy2?

第三种可能性是创造性地混合Python-strings-as-R-code：

data = ["red/blue", "green", "red/green", "blue/red", "red/blue", "green", "red/green", "blue/red", "red/blue", "green", "red/green", "blue/red", "red/blue", "green", "red/green", "blue/red", "red/blue", "green"]
data_vector = robjects.StrVector(data)
# binding the R vector to a symbol in R's "GlobalEnv"
robjects.globalenv['mydata'] = data_vector
# the call is now in a Python string that is evaluated as R code
data_table = robjects.r("multi.split(data_vector, split_char='/')")

使用rpy2运行R函数时出错

1 个答案: