Error in eval expr envir enclos object not found

Question

I cannot understand what is going wrong here    data train  lt - read table  Assign2 WineComplete csv  sep     header T    Building decision tree Train  lt - data frame residual sugar data train residual sugar                  total sulfur dioxide data train total sulfur dioxide                   alcohol data train alcohol                  quality data train quality  Pre  lt - as formula  pre   quality    fit  lt - rpart Pre  method  class  data Train    I am getting the following error     Error in eval expr  envir  enclos    object  pre  not found

User · Answer

This can happen if you don t attach your dataset

User · Answer

Don t know why  Janos deleted his answer  but it s correct  your data frame Train doesn t have a column named pre  When you pass a formula and a data frame to a model-fitting function  the names in the formula have to refer to columns in the data frame  Your Train has columns called residual sugar  total sulfur  alcohol and quality  You need to change either your formula or your data frame so they re consistent with each other   And just to clarify  Pre is an object containing a formula  That formula contains a reference to the variable pre  It s the latter that has to be consistent with the data frame

User · Answer

I think I got what I was looking for     data train  lt - read table  Assign2 WineComplete csv  sep     header T  fit  lt - rpart quality      method  class  data data train  plot fit  text fit  use n TRUE  summary fit

User · Answer

i use      colname train    paste  A   colname train   and it turns out to the same problem as yours   I finally figure out that randomForest is more stingy than rpart  it can t recognize the colname with space  comma or other specific punctuation   paste function will prepend  A  and     as seperator with each colname  so we need to avert the space and use this sentence instead   colname train    paste  A   colname train   sep         this will prepend string without space

[r] Error in eval(expr, envir, enclos) : object not found

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