Please direct questions and comments about these pages, and the R-project in general, to Dr. Much environmental data is either large or complex, and thus requires different approaches than reading a tab or comma delimited file.Understanding data objects in R is important--for some applications, it is not enough to get the data into R, the data must be imported into an object with the right structure and attributes.
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Note that read.table() will return an error if not all lines have the full set of values for variables.
This is common for data from spreadsheets when the last (right) columns have missing values.
⇑ To Top of Page By default, only blanks are read as missing values.
If you have some other indication for a missing value, you need to let R know what that missing value character is by specifying na.strings: Fixed-column data can be imported via read.fwf().
Columns are specified as a list of field widths instead of Fortran formats or COBOL descriptors, you may need to define dummy variables to discard unwanted columns, or use read.fortran.
Also, column/variable names don't generally fit in the column widths, so it is common to read the data into a data object, then assign names to the vectors in that object: If your file happens to be documented with a Fortran FORMAT statement, you can use read.fortran().
⇑ To Top of Page The complete ITIS database of recognized taxonomic units is available from: The MS SQL version not only cannot be imported to MS Access, and at least the June 2008 version cannot be loaded into MS SQL server via the directions given: the schema and instructions tables do not match with the actual tables provided.
The menu commands in Rcommander handle most simple cases of loading data from a file into an R dataframe.
The underlying functions tend to have more optional parameters and much greater flexibility and funcitonality.
read.table() and scan() functions are sufficient for handling data in simple delimited text files.
read.table() is intelligent enough to determine the data types of each variable, and if the variable names are in the first row, they can be directly assigned to the vector objects: This is more commonly useful for ftp access via ftp:// urls.