Look up value based on partial string match in R - r

Question

I have a table (table 1) with a bunch of cities (punctuation, capitalization and spaces have been removed).
I want to scan through the 2nd table (table 2) and pull out any record (the first) that exactly matches or contains the string anywhere within it.
# Table 1
city1
1 waterloo
2 kitchener
3 toronto
4 guelph
5 ottawa
# Table 2
city2
1 waterlookitchener
2 toronto
3 hamilton
4 cityofottawa
This would give the 3rd table seen below.
# Table 3
city1 city2
1 waterloo waterlookitchener
2 kitchener waterlookitchener
3 toronto toronto
4 guelph <N/A>
5 ottawa cityofottawa

Answer 1

I believe there are more sophisticated ways of completing your task, but here is a simple approach using tidyverse.
df <- read_table2("city1
waterloo
kitchener
toronto
guelph
ottawa")
df2 <- read_table2("city2
waterlookitchener
toronto
hamilton
cityofottawa")
df3 <- df$city1 %>%
lapply(grep, df2$city2, value=TRUE) %>%
lapply(function(x) if(identical(x, character(0))) NA_character_ else x) %>%
unlist
df3 <- cbind(df, df3)
Search for every element of df$city1 in df2$city2 (partial or complete match) and return this element of df2$city2. See ?grep for more information.
Replace the character(0) (element not found) with NA. See How to convert character(0) to NA in a list with R language? for details.
Convert list into a vector (unlist).
Attach result to list of cities (cbind).

Answer 2

You can also try using fuzzyjoin. In this case, you can use the function stri_detect_fixed from stringi package to identify at least one occurrence of a fixed pattern in a string.
library(fuzzyjoin)
library(stringi)
library(dplyr)
fuzzy_right_join(table2, table1, by = c("city2" = "city1"), match_fun = stri_detect_fixed) %>%
select(city1, city2)
Output
city1 city2
1 waterloo waterlookitchener
2 kitchener waterlookitchener
3 toronto toronto
4 guelph <NA>
5 ottawa cityofottawa
Data
table1 <- structure(list(city1 = c("waterloo", "kitchener", "toronto",
"guelph", "ottawa")), class = "data.frame", row.names = c(NA,
-5L))
table2 <- structure(list(city2 = c("waterlookitchener", "toronto", "hamilton",
"cityofottawa")), class = "data.frame", row.names = c(NA, -4L
))