Remove backslashes from character string

by

Perhaps you would like to see a different representation of the same string:

test2 <- 'select case when "est"  dsaf'
test<- "select case when \"est\"  dsaf"
identical(test, test2)
#[1] TRUE

When a character value is built with double quotes, any interior instances of \" become only double-quotes. They will be displayed by print (and by the REPL that you see in an interactive session) with the escape-backslash, but using cat you cant determine that they are not really in there as backslashes.

Further proof:

>  nchar("\"")
[1] 1

You can use either cat or print with quote=FALSE in you want to display the value as it really exists internally:

> print(test, quote=FALSE)
[1] select case when "est"  dsaf

This is evidence that at least one version of “SQL” agrees (or “accepts”) that there is no backslash when \" appears in the interior of a string:

> require(sqldf)
Loading required package: sqldf
Loading required package: gsubfn
Loading required package: proto
Loading required package: RSQLite
Loading required package: DBI
> ?sqldf
> a1r <- head(warpbreaks)
> a1s <- sqldf("select * from warpbreaks limit 6")
Loading required package: tcltk
> a2s <- sqldf("select * from CO2 where Plant like 'Qn%'")
> 
> a2sdq <- sqldf("select * from CO2 where Plant like \"Qn%\"")
> identical(a2s,a2sdq)
[1] TRUE

So the was the first problem. The second problem was trying to assign the value of a cat call. The cat function always returns NULL after sending its value to a destination, possibly the console output. You cannot save the resulting character value to an R name. You always get NULL. See the ?cat help page.

More Related Contents:

  1. Reshaping data.frame from wide to long format
  2. ggplot with 2 y axes on each side and different scales
  3. How to add leading zeros?
  4. Quickly reading very large tables as dataframes
  5. Order discrete x scale by frequency/value
  6. Combine two data frames by rows (rbind) when they have different sets of columns
  7. Counting unique / distinct values by group in a data frame
  8. Apply several summary functions on several variables by group in one call
  9. How to debug “contrasts can be applied only to factors with 2 or more levels” error?
  10. How to use a variable to specify column name in ggplot
  11. Formatting Decimal places in R
  12. How can I trim leading and trailing white space?
  13. Determine path of the executing script
  14. ggplot2 line chart gives “geom_path: Each group consist of only one observation. Do you need to adjust the group aesthetic?”
  15. How to name variables on the fly?
  16. Cleaning up factor levels (collapsing multiple levels/labels)
  17. Plot multiple columns on the same graph in R [duplicate]
  18. Concatenate a vector of strings/character
  19. How to generate permutations or combinations of object in R?
  20. Numeric comparison difficulty in R
  21. Convert data.frame column format from character to factor
  22. Subset rows in a data frame based on a vector of values
  23. Convert UNIX epoch to Date object
  24. How to plot a function curve in R
  25. Use variable names in functions of dplyr
  26. Access variable value where the name of variable is stored in a string
  27. What do the %op% operators in mean? For example “%in%”?
  28. Display exact value of a variable in R
  29. What does “Error: object ” not found” mean?
  30. Is there anything wrong with using T & F instead of TRUE & FALSE?

Leave a Comment