R – dplyr: select all variables except for those contained in vector

dplyrrselect

This should be a simple issue but I am struggling.

I have a vector of variable names that I want to exclude from a data frame:

df <- data.frame(matrix(rexp(50), nrow = 10, ncol = 5))
names(df) <- paste0(rep("variable_", 5), 1:5)

excluded_vars <- c("variable_1", "variable_3")

I would have thought that just excluding the object in the select statement with - would have worked:

select(df, -excluded_vars)

But I get the following error:

Error in -excluded_vars : invalid argument to unary operator

the same is true when using select_()

Any ideas?

Best Answer

You need to use the one_of function:

select(df, -one_of(excluded_vars))

See the section on Useful Functions in the dplyr documentation for select for more about selecting based on variable names.

Related Solutions

Mysql – Select all columns except one in MySQL

Actually there is a way, you need to have permissions of course for doing this ...

SET @sql = CONCAT('SELECT ', (SELECT REPLACE(GROUP_CONCAT(COLUMN_NAME), '<columns_to_omit>,', '') FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = '<table>' AND TABLE_SCHEMA = '<database>'), ' FROM <table>');

PREPARE stmt1 FROM @sql;
EXECUTE stmt1;

Replacing <table>, <database> and <columns_to_omit>

R – How to remove rows of a matrix by row name, rather than numerical index

When working with indexing, you cannot use "negative" character vectors. You can convert to logical with %in%

g[!rownames(g) %in% remove, ]  # ! is logical negation

If you really wanted to use negative-indexing this could be done:

g[-which(rownames(g) %in% remove), ] #which converts to numeric, so minus sign OK

... however it has a nasty potential erroneous result that arises when there are not any rownames in the target vector. The result may be no values returned.

Best Answer

Related Solutions

Mysql – Select all columns except one in MySQL

R – How to remove rows of a matrix by row name, rather than numerical index

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