rd, Read2Reads the contents of the specified data file with optional variable labels into an R data table (frame). By default the format of the file is detected from its filetype: comma separated value text file from .csv, SPSS data file from .sav, or R data file from .rda. If no filetype is assigned then the file type defaults to a csv file, which can also recognize tab-limited data files as well. A fixed width formatted text data file can also be read by specifying the required R widths option. Identify the file by either browsing for the file on the local computer system with Read(), or identify the file with a character string in the form of a path name or a web URL. Variable labels can be added to the data table when reading a text file, and any variable labels in a native SPSS file are automatically included.
The function also provides feedback regarding the read data, which includes the variable names, the dimensions of the resulting data frame, the data type for each variable, and the values of the variables in the data file for the first and last rows of the data. In addition, an analysis of missing data is provided, listing the number of missing values for each variable and for each observation.
Also see the lessR function corRead to read a correlation matrix.
Read(ref=NULL, format=c("csv", "SPSS", "R", "lessR"), labels=NULL, widths=NULL, missing="", n.mcut=1,
miss.show=30, miss.zero=FALSE, miss.matrix=FALSE,
max.lines=30, quiet=getOption("quiet"), ...)
rd(...)
Read2(..., sep=";", dec=",")
http://.csv file, which
also will recognize tab-delimited text. As an option can be an SPSS .sav file,
which also reads the variable labels if present, or a native R drow2, then
the labels are in the second line of the data file.n.mcut.TRUE, no text output. Can change the corresponding system
default with set function.read.table function for text files, with row.names and header.mydata as in the examples below. This is the default name for the data frame input into the lessR data analysis functions.Read reads text data files which are either comma delimited, csv, or tab-dilimited data files, native R files with file type of .rda and native SPSS files with file type .sav. Invoke the widths option to allow for the reading of fixed width formatted data. Calls the lessR function details to provide feedback regarding details of the data frame that was read.CREATE csv FILE One way to create a csv data file is to enter the data into a text editor. A more structured method is to use a worksheet application such as MS Excel, LibreOffice Calc. Place the variable names in the first row of the worksheet. Each column of the worksheet contains the data for the corresponding variable. Each subsequent row contains the data for a specific observation, such as for a person or a company.
All numeric data in the worksheet should be displayed in the General format, so that the only non-digit character for a numeric data value is a decimal point. The General format removes all dollar signs and commas, for example, leaving only the pure number, stripped of these extra characters which R will not properly read as part of a numeric data value.
To create the csv file from a standard worksheet application such as Microsoft Excel or LibreOffice Calc, first convert any numeric data to general format to remove characters such as dollar signs and commas, and then under the File option, do a Save As and choose the csv format.
Call help(read.table) to view the other options that can also be implemented from Read.
MECHANICS
Specify the file as with the Read function for reading the data into a data frame. If no arguments are passed to the function, then interactively browse for the file. Or, enclose within quotes a full path name or a URL for reading the labels on the web.
Given a csv data file, or tab-delimted text file, read the data into an R data frame called mydata with Read. Because Read calls the standard R function read.csv, which serves as a wrapper for read.table, the usual options that work with read.table, such as row.names, also can be passed through the call to Read.
SPSS DATA
Relies upon read.spss from the foreign package. To read data in the SPSS .sav format. If the file has a file type of .sav, that is, the file specification ends in .sav, then the format is automatically set to "SPSS". To invoke this option for a relevant data file of any file type, explicitly specify format="SPSS". Any variable labels in the SPSS file are read and stored in the resulting R data table (frame).
R DATA
Relies upon the standard R function load. By convention only, data files in native R format have a file type of .rda. To read a native R data file, if the file type is .rda, the format is automatically set to "R". To invoke this option for a relevant data file of any file type, explicitly specify format="R". Create a native R data file by saving the current data frame, usually mydata, with the lessR function Write.
lessR DATA
lessR has some data sets included with the package. Read reads each such data set by specifying its name and setting format="lessR". Also, each included data set begins with the prefix dat, which can be deleted when specifying the name of the data set. This option is a replacement for the standard R data function, offering the added information provided by Read.
FIXED WIDTH FORMATTED DATA
Relies upon read.fwf. Sometimes the width of the columns are the same for all the data values of a variable, such as a data file of Likert scale responses from 1 to 5 on a 50 item survey such that the data consist of 50 columns with no spaces or other delimiter to separate adjacent data values. To read this data set, invoke the widths option of that function.
MISSING DATA
By default, Read provides a list of each variable and each row with the display of the number of associated missing values, indicated by the standard R missing value code NA. When reading the data, Read automatically sets any empty values as missing. Note that this is different from the R default in read.table in which an empty value for character string variables are treated as a regular data value. Any other valid value for any data type can be set to missing as well with the missing option. To mimic the standard R default for missing character values, set missing=NA.
To not list the variable name or row name of variables or rows without missing data, invoke the miss.zero=FALSE option, which can appreciably reduce the amount of output for large data sets. To view the entire data table in terms of 0's and 1's for non-missing and missing data, respectively, invoke the miss.matrix=TRUE option.
VARIABLE LABELS
Unlike standard R, lessR provides for variable labels, which can be provided for some or all of the variables in a data frame. One way to enter the variable labels is to read them from their own file with Read with labels set to the full path name or URL of the labels file, or just the file name if the labels file is in the same directory as the data file. Another method is to include the labels directly in text data file. To to this, specify the label of variable labels with the label="row2" option. The web survey application Qualtrics downloads csv files in this format. These labels options work for csv files. Variable labels in an SPSS data file are automatically read into the corresponding R data frame. The labels are stored within the data frame, so if the data frame is written to an external file as a native R data file, the labels are also written as part of that file.
For a file that contains only labels, each row of the file, including the first row, consists of the variable name, a comma, and then the label, that is, the standard csv format such as obtained with the csv option from a standard worksheet application such as Microsoft Excel or LibreOffice Calc. Not all variables in the data frame that contains the data, usually mydata, need have a label, and the variables with their corresponding labels can be listed in any order. An example of this file follows for four variables, I1 through I4, and their associated labels.
I2,This instructor presents material in a clear and organized manner. I4,Overall, this instructor was highly effective in this class. I1,This instructor has command of the subject. I3,This instructor relates course materials to real world situations. If there is a comma in the variable label, then the label needs to be enclosed in quotes.
The lessR functions that provide analysis, such as Histogram for a histogram, automatically include the variable labels in their output, such as the title of a graph. Standard R functions can also use these variable labels by invoking the lessR function label, such as setting main=label(I4) to put the variable label for a variable named I4 in the title of a graph.
read.csv,read.spss,
read.fwf, corRead,
details.# remove the # sign before each of the following Read statements to run
# to browse for a csv data file on the computer system, invoke Read with
# the ref argument empty
# mydata <- Read()
# abbreviated name
# mydata <- rd()
# same as above, but include standard read.csv options to indicate
# no variable names in first row of the csv data file
# and then provide the names
# also indicate that the first column is an ID field
# mydata <- Read(header=FALSE, col.names=c("X", "Y"), row.names=1)
# read a csv data file from the web
# mydata <- Read("http://web.pdx.edu/~gerbing/data/twogroup.csv")
# read a csv data file with -99 and XXX set to missing
# mydata <- Read(missing=c(-99, "XXX"))
# do not display any output
# mydata <- rd.quiet()
# read tab-delimited (or any other white-space) data
# mydata <- Read(sep="")
# read the built-in data set datEmployee
mydata <- Read("Employee", format="lessR")
# read a data file that consists of a
# 5 column ID field, 2 column Age field
# and 75 single columns of data, no spaces between columns
# name the variables with lessR function: to
# the variable names are Q01, Q02, ..., Q74, Q75
# mydata <- Read(widths=c(5,2,rep(1,75)), col.names=c("ID", "Age", to("Q", 75)))Run the code above in your browser using DataLab