lookup.pctile: Find approx wtd percentiles in lookup table that is in memory

In ejanalysis/ejanalysis: Tools for Environmental Justice (EJ) Analysis

Find approx wtd percentiles in lookup table that is in memory

Description

This is used with lookup or us, a data.frame that is a lookup table created by write.pctiles(), write.pctiles.by.zone(), write.wtd.pctiles(), or write.wtd.pctiles.by.zone(). The data.frame us or lookup must have a field called "PCTILE" that contains quantiles/percentiles and other column(s) with values that fall at those percentiles. This function accepts lookup table (or uses one called us if that is in memory), and finds the number in the PCTILE column that corresponds to where a specified value (in myvector) appears in the column called varname.in.lookup.table. The function just looks for where the specified value fits between values in the lookup table and returns the approximate percentile as found in the PCTILE column. If the value is between the cutpoints listed as percentiles 89 and 90, it returns 89, for example. If the value is exactly equal to the cutpoint listed as percentile 90, it returns percentile 90. If the value is less than the cutpoint listed as percentile 0, which should be the minimum value in the dataset, it still returns 0 as the percentile, but with a warning that the value checked was less than the minimum in the dataset.

Usage

lookup.pctile(myvector, varname.in.lookup.table, lookup, zone)

Arguments

myvector	Numeric vector, required. Values to look for in the lookup table.
varname.in.lookup.table	Character element, required. Name of column in lookup table to look in to find interval where a given element of myvector values is.
lookup	Either lookup must be specified, or a lookup table called us must already be in memory. This is the lookup table data.frame with a PCTILE column and column whose name is the value of varname.in.lookup.table.
zone	Character element (or vector as long as myvector), optional. If specified, must appear in a column called REGION within the lookup table. For example, it could be 'NY' for New York State.

Value

By default, returns numeric vector length of myvector.

See Also

write.pctiles(), write.pctiles.by.zone(), write.wtd.pctiles(), and write.wtd.pctiles.by.zone()

Examples

  lookup.pctile(myvector = c(-99, 0, 500, 801, 949.9, 1000, 99999),
    lookup = data.frame(PCTILE = 0:100,
    myvar = 10*(0:100),
    REGION = 'USA', stringsAsFactors = FALSE), varname.in.lookup.table = 'myvar')
 ## Not run: 
   What is environmental score at given percentile?
 ejanalysis::lookup.pctile(40,'cancer',lookupUSA)
 #   84
 ejanalysis::lookup.pctile(40,'cancer',lookupStates,'WV')
 #   93
 #    What is percentile of given environmental score?
 ejscreen::lookupUSA[lookupUSA$PCTILE=='84' ,'cancer']
 #   39.83055
 ejscreen::lookupStates[lookupStates$PCTILE=='84' & lookupStates$REGION =='WV','cancer']
 #   33.36371
 # also see ejanalysis::assign.pctiles
 
## End(Not run)
  ## Not run: 
     library(ejscreen)
       evarname <- 'traffic.score'
       evalues <- bg21[ , evarname]
       emax <- max(evalues,na.rm = TRUE)
       plot(lookupUSA[,evarname], lookupUSA$PCTILE, xlab = evarname,
       main='contents of lookup table', type='b')

       plot(x = (1:1000) * (emax / 1000),
        y = lookup.pctile(myvector = (1:1000) * emax / 1000, varname.in.lookup.table = evarname,
        lookup = lookupUSA),
        ylim = c(0,100),   type='b',
        xlab=evarname, ylab='percentile per lookup table' ,
        main='Percentiles for various envt scores, as looked up in lookup table')
      abline(v = lookupUSA[ lookupUSA$PCTILE == 'mean', evarname])

  
## End(Not run)

ejanalysis/ejanalysis documentation built on April 2, 2024, 10:12 a.m.