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rdataframepalindrome

Find palindromic words in a dataframe

I am trying to find all the palindromic words in a column in a data frame 'data' which looks like:

name year amount 
 James 2010  934706
 Aza   2010  21042
 Rory  2010   869691
 Suzanne 2010 651674
 Felicity 2010 386115
 Oliver   2010  382388
 Anna     2010   43211

I have tried:

palindrome <- function(word) {
rawWord <- charToRaw(tolower(word)) ## converts to lower case
 sprintf("%s is %sa palindrome", word,
    c("not ", "")[identical(rawWord, rev(rawWord)) + 1])
     }
palindrome(data)

But this returns a list of "mary is not a palindrome" "anna is not a palindrome" ... etc I want to be able to subset only the words that are palindromic and then return them to the data frame in order to correlate them to the other columns to find when they occured and how many times.

Solution

  • You can do the following steps. 

    rawdata <- sapply(tolower(data$name), charToRaw)

# Array of booleans. TRUE if palindromic. FALSE if not
ispalindrom <- unlist(lapply(rawdata, function(x) identical(x, rev(x))))

# Palindromic words
data[ispalindrom,]

# Non palindromic words
data[! ispalindrom,]