使用rpy2运行R函数时出错

debugcn 发表于 Dev

什洛米兰

我试图用rpy2要逃避的multi.split功能questionr包。

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，出现以下错误：

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]

我认为这与我要发送的向量的大小有关，因为如果我删除了最后一个项目

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。同样，如果我更改了“ split_char”变量，例如：

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

无论我发送的数组大小如何，我都不会收到错误消息。

我试图直接在R中运行匹配的代码（使用R-Studio），但运行没有问题。关于如何解决此问题的任何想法？

lgautier

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

R函数的签名是：

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

他的文档mnames是：

产生的变种的名称。如果为NULL，则根据原始变量名称和答案计算名称。

在调用中multi_split(data_vector, split_char='/')，嵌入式R无法看到变量名，因为这是Python调用，并且data_vector是匿名变量（仅内容，无变量名）。

我虽然可以指定mnames，但是您检查了一下，但不起作用（请参阅下面的评论）。这就是代码似乎要说的：vname <- deparse(substitute(var))无论是否指定了mnames，都会对行进行评估：https : //github.com/juba/questionr/blob/9cf09f3ffcd6c8df24182380f12d52b061c221ef/R/table.multi.R#L161

另一种方法是计算R表达式的用法。一个较旧的帖子应该为此提供必要的信息：哪个对象从rpy2传递给R？

第三种可能性是创造性地将Python字符串作为R代码进行混合：

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='/')")

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