how to identify locations from text

问题

Here is sample to my function that getscodes

df= read.csv("secondary.csv",header = TRUE)

回答1:

S <- "s / O sk hungu 101 / 90 MODEL HOUSE TALAB GAGNI SHUKUL LUCKNOW UTTAR PRADESH LUCKNOW UTTAR PRADESH 226001"

I recommend making all possible N-x strings where N is length of your string and x is variable length

allchr <- unlist(strsplit(S, ""))
listsubstr <- sapply(1:length(allchr), function(I) paste0(allchr[I:length(allchr)], collapse=""))

  # [1] "s / O sk hungu 101 / 90 MODEL HOUSE TALAB GAGNI SHUKUL LUCKNOW UTTAR PRADESH LUCKNOW UTTAR PRADESH 226001"
  # [2] " / O sk hungu 101 / 90 MODEL HOUSE TALAB GAGNI SHUKUL LUCKNOW UTTAR PRADESH LUCKNOW UTTAR PRADESH 226001" 
  # [3] "/ O sk hungu 101 / 90 MODEL HOUSE TALAB GAGNI SHUKUL LUCKNOW UTTAR PRADESH LUCKNOW UTTAR PRADESH 226001"  
  # [4] " O sk hungu 101 / 90 MODEL HOUSE TALAB GAGNI SHUKUL LUCKNOW UTTAR PRADESH LUCKNOW UTTAR PRADESH 226001" 

You can iterate through this list to check for valid geocodes. I have to provide pseudocode since I'm not sure how to check if a string is a valid geocode.

sapply(listsubstr, function(I) is.geocode(I))     # contains pseudocode

You could also do this with recursion though.

myfun <- function(x) {
             if (x is gecode) { # contains pseudocode
                   return(x)
             } else {
                   myfun(substr(x, 2, nchar(S)))
             }
         }

来源：https://stackoverflow.com/questions/46359191/how-to-identify-locations-from-text