R 将数值上传到 boolean 列 - 为什么？

Question

I want to upload an Excel file as a dataframe in R. It is a large file with a lot of numbers and some #NV values.

The upload works good for the majority of columns (in total, there are 4,000 columns). But for some columns, R changes the columns to "TRUE" or "FALSE", creating a boolean column.

I don't want that, since all of the columns are supposed to be numeric.

Do you know why R does that?

Answer 1

It would really help if you provided code snippets, because there are many different excel-to-dataframe libraries/methods/behaviors.

But assuming that you are using writexl , the read_excel function has a guess_max parameter for this kind of case. guess_max is 1000 by default.

Try df <- read_excel(path = filepath, sheet = sheet_name, guess_max = 100000)

Since dataframes cannot have different data types in the same column, read_excel has to read your excel file and guess what data type each column should be, before actually filling the dataframe. If a column happens to only have NA values in the first 1000 rows, read_excel will assume you have a column of booleans, and then all subsequent values encountered in future rows will be cast accordingly. So if you set guess_max to something huge, you make read_excel slower, but it might avoid the casting of numerics to booleans.