Creating an indicator variable using partial string matching

Question

I am trying to create an indicator variables for different races/ethnicities in my data. In my data ('mydata') I have a variable called "Race". This variable has the output for every box a person marked under race on a questionnaire. So it looks something like this:

ID   Race
6    American Indian or Alaska Native, Black or African American, Hispanic or Latino
7    Hispanic or Latino
10   Native Hawaiian or Other Pacific Islander
11   Hispanic or Latino, White
29   White
30   Black or African American
31   American Indian or Alaska Native, Hispanic or Latino, White

I want to create a variable so that if someone for example said that they were Hispanic, ignoring what else they said, under the new "Hispanic" variable they would get a "1" or if they did not say they were Hispanic then "Hispanic" would get a 0.

I know this entails using partial string matching but I am having difficulty getting the output that I would like. I have made multiple attempts with little luck. Here is the code for my last attempt:

if(mydata[grep("Hispanic", mydata$Race)]) {
  Hispanic<-1
 } else {
  Hispanic<-0
 }

Henrik · Accepted Answer · 2014-10-07 20:04:30Z

5

You may use grepl which "returns a logical vector (match or not for each element of x)" (from ?grepl). The resulting logical vector can then be converted to 0 (FALSE) or 1 (TRUE) by using as.integer:

mydata$Hispanic <- as.integer(grepl(pattern = "Hispanic", x = mydata$Race))
mydata$Hispanic
# [1] 1 1 0 1 0 0 1

answered Oct 7, 2014 at 20:04

Henrik

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1 Comment

user3008983 Over a year ago

Well, Henrik, I am ashamed at how simple the code is. It is exactly what I needed. Thank you for taking the time to answer my question!

KFB · Accepted Answer · 2014-10-07 20:34:04Z

4

Another option:

re-create the data

mydata <- read.table(
  header = T, con <- textConnection
  ('
ID Race
6 "American Indian or Alaska Native, Black or African American, Hispanic or Latino"
7 "Hispanic or Latino"
   10 "Native Hawaiian or Other Pacific Islander"
   11 "Hispanic or Latino, White"
   29 "White"
   30 "Black or African American"
   31 "American Indian or Alaska Native, Hispanic or Latino, White"
   '), stringsAsFactors = FALSE, fill = TRUE, strip.white = TRUE)
close(con)

Use data.table

library(data.table)
setDT(mydata); setkey(mydata, Race)
mydata[grep("hispanic", Race, ignore.case=T), Race_x := 1]
mydata[is.na(Race_x), Race_x := 0][]

   ID                                                                            Race Race_x
1:  6 American Indian or Alaska Native, Black or African American, Hispanic or Latino      1
2: 31                     American Indian or Alaska Native, Hispanic or Latino, White      1
3: 30                                                       Black or African American      0
4:  7                                                              Hispanic or Latino      1
5: 11                                                       Hispanic or Latino, White      1
6: 10                                       Native Hawaiian or Other Pacific Islander      0
7: 29                                                                           White      0

answered Oct 7, 2014 at 20:34

KFB

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1 Comment

user3008983 Over a year ago

Interesting, this would be useful from some of my other data cleaning as well. Thanks for the response.

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Creating an indicator variable using partial string matching

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re-create the data

Use data.table

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