The R Book

Common Errors when Using read.table

It is important to note that read.table would fail if there were any spaces in any of the variable names in row 1 of the dataframe (the header row, see p. 107), such as Field Name, Soil pH or Worm Density, or between any of the words within the same factor level (as in many of the field names). You should replace all these spaces by dots ‘.’ before saving the dataframe in Excel (use Edit/Replace with " " replaced by " . "). Now the dataframe can be read into R. There are three things to remember:

• The whole path and file name needs to be enclosed in double quotes: "c:\\abc.txt".
• header=T says that the first row contains the variable names.
• Always use double backslash \\ rather than \ in the file path definition.

The commonest cause of failure is that the number of variable names (characters strings in row 1) does not match the number of columns of information. In turn, the commonest cause of this is that you have blank spaces in your variable names:

state name population home ownership cars insurance

This is wrong because R expects seven columns of numbers when there are only five. Replace the spaces within the names by dots and it will work fine:

state.name population home.ownership cars insurance

The next most common cause of failure is that the data file contains blank spaces where there are missing values. Replace these blanks with NA in Excel (or use a different separator symbol: see below).

Finally, there can be problems when you are ...