Return a data.frame with the columns “name”,
“cponame”, “category”, “subcategory”,
“description”.
Categories and subcategories are:
| category | subcategory | description |
| meta | CPO that acts on other CPOs | |
| tools | ||
| data | general | |
| general data preproc | ||
| factor data preproc | ||
| numeric data preproc | ||
| feature conversion | ||
| cleanup | ||
| featurefilter | general | fltr CPO with operation arg |
| specialised | specific feat filter CPO | |
| imputation | general | imp CPO with operation arg |
| specialised | specific imputation CPO | |
| tools | imputation |
listCPO()