upData: Update a Data Frame or Cleanup a Data Frame after Importing

In Hmisc: Harrell Miscellaneous

Update a Data Frame or Cleanup a Data Frame after Importing

Description

cleanup.import will correct errors and shrink the size of data frames. By default, double precision numeric variables are changed to integer when they contain no fractional components. Infinite values or values greater than 1e20 in absolute value are set to NA. This solves problems of importing Excel spreadsheets that contain occasional character values for numeric columns, as S converts these to Inf without warning. There is also an option to convert variable names to lower case and to add labels to variables. The latter can be made easier by importing a CNTLOUT dataset created by SAS PROC FORMAT and using the sasdict option as shown in the example below. cleanup.import can also transform character or factor variables to dates.

upData is a function facilitating the updating of a data frame without attaching it in search position one. New variables can be added, old variables can be modified, variables can be removed or renamed, and "labels" and "units" attributes can be provided. Observations can be subsetted. Various checks are made for errors and inconsistencies, with warnings issued to help the user. Levels of factor variables can be replaced, especially using the list notation of the standard merge.levels function. Unless force.single is set to FALSE, upData also converts double precision vectors to integer if no fractional values are present in a vector. upData is also used to process R workspace objects created by StatTransfer, which puts variable and value labels as attributes on the data frame rather than on each variable. If such attributes are present, they are used to define all the labels and value labels (through conversion to factor variables) before any label changes take place, and force.single is set to a default of FALSE, as StatTransfer already does conversion to integer.

Variables having labels but not classed "labelled" (e.g., data imported using the haven package) have that class added to them by upData.

The dataframeReduce function removes variables from a data frame that are problematic for certain analyses. Variables can be removed because the fraction of missing values exceeds a threshold, because they are character or categorical variables having too many levels, or because they are binary and have too small a prevalence in one of the two values. Categorical variables can also have their levels combined when a level is of low prevalence. A data frame listing actions take is return as attribute "info" to the main returned data frame.

Usage

cleanup.import(obj, labels, lowernames=FALSE, 
               force.single=TRUE, force.numeric=TRUE, rmnames=TRUE,
               big=1e20, sasdict, print, datevars=NULL, datetimevars=NULL,
               dateformat='%F',
               fixdates=c('none','year'),
               autodate=FALSE, autonum=FALSE, fracnn=0.3,
               considerNA=NULL, charfactor=FALSE)

upData(object, ..., 
       subset, rename, drop, keep, labels, units, levels, force.single=TRUE,
       lowernames=FALSE, caplabels=FALSE, moveUnits=FALSE,
       charfactor=FALSE, print=TRUE, html=FALSE)

dataframeReduce(data, fracmiss=1, maxlevels=NULL,  minprev=0, print=TRUE)

Arguments

obj	a data frame or list
object	a data frame or list
data	a data frame
force.single	By default, double precision variables are converted to single precision (in S-Plus only) unless force.single=FALSE. force.single=TRUE will also convert vectors having only integer values to have a storage mode of integer, in R or S-Plus.
force.numeric	Sometimes importing will cause a numeric variable to be changed to a factor vector. By default, cleanup.import will check each factor variable to see if the levels contain only numeric values and "". In that case, the variable will be converted to numeric, with "" converted to NA. Set force.numeric=FALSE to prevent this behavior.
rmnames	set to ‘F’ to not have ‘cleanup.import’ remove ‘names’ or ‘.Names’ attributes from variables
labels	a character vector the same length as the number of variables in obj. These character values are taken to be variable labels in the same order of variables in obj. For upData, labels is a named list or named vector with variables in no specific order.
lowernames	set this to TRUE to change variable names to lower case. upData does this before applying any other changes, so variable names given inside arguments to upData need to be lower case if lowernames==TRUE.
big	a value such that values larger than this in absolute value are set to missing by cleanup.import
sasdict	the name of a data frame containing a raw imported SAS PROC CONTENTS CNTLOUT= dataset. This is used to define variable names and to add attributes to the new data frame specifying the original SAS dataset name and label.
print	set to TRUE or FALSE to force or prevent printing of the current variable number being processed. By default, such messages are printed if the product of the number of variables and number of observations in obj exceeds 500,000. For dataframeReduce set print to FALSE to suppress printing information about dropped or modified variables. Similar for upData.
datevars	character vector of names (after lowernames is applied) of variables to consider as a factor or character vector containing dates in a format matching dateformat. The default is "%F" which uses the yyyy-mm-dd format.
datetimevars	character vector of names (after lowernames is applied) of variables to consider to be date-time variables, with date formats as described under datevars followed by a space followed by time in hh:mm:ss format. chron is used to store date-time variables. If all times in the variable are 00:00:00 the variable will be converted to an ordinary date variable.
dateformat	for cleanup.import is the input format (see strptime)
fixdates	for any of the variables listed in datevars that have a dateformat that cleanup.import understands, specifying fixdates allows corrections of certain formatting inconsistencies before the fields are attempted to be converted to dates (the default is to assume that the dateformat is followed for all observation for datevars). Currently fixdates='year' is implemented, which will cause 2-digit or 4-digit years to be shifted to the alternate number of digits when dateform is the default "%F" or is "%y-%m-%d", "%m/%d/%y", or "%m/%d/%Y". Two-digits years are padded with 20 on the left. Set dateformat to the desired format, not the exceptional format.
autodate	set to TRUE to have cleanup.import determine and automatically handle factor or character vectors that mainly contain dates of the form YYYY-mm-dd, mm/dd/YYYY, YYYY, or mm/YYYY, where the later two are imputed to, respectively, July 3 and the 15th of the month. Takes effect when the fraction of non-dates (of non-missing values) is less than fracnn to allow for some free text such as "unknown". Attributes special.miss and imputed are created for the vector so that describe() will inform the user. Illegal values are converted to NAs and stored in the special.miss attribute.
autonum	set to TRUE to have cleanup.import examine (after autodate) character and factor variables to see if they are legal numerics exact for at most a fraction of fracnn of non-missing non-numeric values. Qualifying variables are converted to numeric, and illegal values set to NA and stored in the special.miss attribute to enhance describe output.
fracnn	see autodate and autonum
considerNA	for autodate and autonum, considers character values in the vector considerNA to be the same as NA. Leading and trailing white space and upper/lower case are ignored.
charfactor	set to TRUE to change character variables to factors if they have fewer than n/2 unique values. Null strings and blanks are converted to NAs.
...	for upData, one or more expressions of the form variable=expression, to derive new variables or change old ones.
subset	an expression that evaluates to a logical vector specifying which rows of object should be retained. The expressions should use the original variable names, i.e., before any variables are renamed but after lowernames takes effect.
rename	list or named vector specifying old and new names for variables. Variables are renamed before any other operations are done. For example, to rename variables age and sex to respectively Age and gender, specify rename=list(age="Age", sex="gender") or rename=c(age=...).
drop	a vector of variable names to remove from the data frame
keep	a vector of variable names to keep, with all other variables dropped
units	a named vector or list defining "units" attributes of variables, in no specific order
levels	a named list defining "levels" attributes for factor variables, in no specific order. The values in this list may be character vectors redefining levels (in order) or another list (see merge.levels if using S-Plus).
caplabels	set to TRUE to capitalize the first letter of each word in each variable label
moveUnits	set to TRUE to look for units of measurements in variable labels and move them to a "units" attribute. If an expression in a label is enclosed in parentheses or brackets it is assumed to be units if moveUnits=TRUE.
html	set to TRUE to print conversion information as html vertabim at 0.6 size. The user will need to put results='asis' in a knitr chunk header to properly render this output.
fracmiss	the maximum permissable proportion of NAs for a variable to be kept. Default is to keep all variables no matter how many NAs are present.
maxlevels	the maximum number of levels of a character or categorical or factor variable before the variable is dropped
minprev	the minimum proportion of non-missing observations in a category for a binary variable to be retained, and the minimum relative frequency of a category before it will be combined with other small categories

Value

a new data frame

Author(s)

Frank Harrell, Vanderbilt University

See Also

sas.get, data.frame, describe, label, read.csv, strptime, POSIXct,Date

Examples

## Not run: 
dat <- read.table('myfile.asc')
dat <- cleanup.import(dat)

## End(Not run)
dat <- data.frame(a=1:3, d=c('01/02/2004',' 1/3/04',''))
cleanup.import(dat, datevars='d', dateformat='%m/%d/%y', fixdates='year')

dat <- data.frame(a=(1:3)/7, y=c('a','b1','b2'), z=1:3)
dat2 <- upData(dat, x=x^2, x=x-5, m=x/10, 
               rename=c(a='x'), drop='z',
               labels=c(x='X', y='test'),
               levels=list(y=list(a='a',b=c('b1','b2'))))
dat2
describe(dat2)
dat <- dat2    # copy to original name and delete dat2 if OK
rm(dat2)
dat3 <- upData(dat, X=X^2, subset = x < (3/7)^2 - 5, rename=c(x='X'))

# Remove hard to analyze variables from a redundancy analysis of all
# variables in the data frame
d <- dataframeReduce(dat, fracmiss=.1, minprev=.05, maxlevels=5)
# Could run redun(~., data=d) at this point or include dataframeReduce
# arguments in the call to redun

# If you import a SAS dataset created by PROC CONTENTS CNTLOUT=x.datadict,
# the LABELs from this dataset can be added to the data.  Let's also
# convert names to lower case for the main data file
## Not run: 
mydata2 <- cleanup.import(mydata2, lowernames=TRUE, sasdict=datadict)

## End(Not run)

Hmisc documentation built on June 22, 2024, 12:19 p.m.