交叉验证：formula.character(object, env = baseenv()) 中的错误：无效的公式

如何解决交叉验证：formula.character(object, env = baseenv()) 中的错误：无效的公式

我正在尝试进行交叉验证，以查看 5 个蘑菇特征中的哪个模型最能预测蘑菇是可食用的还是有毒的。我正在尝试使用 allCombs 函数遍历所有可能的组合以获取蘑菇特征。

这是我得到的错误：

Error in formula.character(object,env = baseenv()) : 
    invalid formula c("CapShape","0","0"): 
         not a call

对我哪里出错的任何帮助将不胜感激，我的代码如下：

idx <- sample(nrow(mushroom_data),4062) #50:50 split between sets.

train_data_mushroom <- mushroom_data[idx,]; test_data_mushroom <- mushroom_data[-idx,]

#all possible models we want to consider
combs <- allCombs(1:5)
combs <- allCombs(c("CapShape","CapSurface","CapColor","odor","Height")) #mushroom features
combs=combs[-1,]
combs[is.na(combs)] <- 0

predictiveloglikelihood3 <- rep(NA,nrow(combs))
for (i in 1:nrow(combs)){
  paste("Edible ~",paste(combs[i,1:5],collapse="+"))
  
current_model <- glm(formula = combs[i,data=train_data_mushroom)

sigma <- sqrt(summary(current_model)$dispersion)

ypredict_mean <- predict(current_model,test_data_mushroom)

  predictiveloglikelihood3[i] <- sum(dnorm(test_data_mushroom$Edible,ypredict_mean,sigma,log=TRUE))

}