Problem with the str_replace function
Hi,
stringr::str_replace() treats the 2nd argument ('pattern') as a regular
expression and some characters have a special meaning when they are used
in a regular expression. For example the dot plays the role of a
wildcard (i.e. it means "any character"):
> str_replace("aaXcc", "a.c", "ZZ")
[1] "aZZc"
If you want to treat a special character literally, you need to escape
it with a double backslahe '\\':
> str_replace(c("aaXcc", "aa.cc"), "a.c", "ZZ")
[1] "aZZc" "aZZc"
> str_replace(c("aaXcc", "aa.cc"), "a\\.c", "ZZ")
[1] "aaXcc" "aZZc"
Turns out that parenthesis are also special characters so you also need
to escape them:
> str_replace("aa(X)cc", "a(X)c", "ZZ")
[1] "aa(X)cc"
> str_replace("aa(X)cc", "a\\(X\\)c", "ZZ")
[1] "aZZc"
There are plenty of example in the man page for str_replace() (see
'?str_replace') including examples showing the use of parenthesis in the
pattern.
Hope this helps,
H.
On 3/16/21 5:34 PM, phil at philipsmith.ca wrote:
I have a problem with the str_replace() function in the stringr package. Please refer to my reprex below. I start with a vector of strings, called x. Some of the strings contain apostrophes and brackets. I make a simple replacement as with x1, and there is no problem. I make another simple replacement, x2, where the pattern string has an apostrophe. Again no problem. Then I make a third replacement, x3, where the pattern has opening and closing brackets and the function still works fine. Finally I make a replacement where the pattern has both an apostrophe and opening and closing brackets and the replacement does not work. I tried to solve this by putting backslashes before the apostrophe and/or the brackets, but that accomplished nothing. I am stumped. # Reprex for str_replace problem library(stringr) x <- c( ? "Clothing and footwear", ? "Women's clothing", ? "Women's footwear (excluding athletic)", ? "Clothing accessories (belts and so on)", ? "Clothing and footwear", ? "Women's clothing", ? "Women's footwear (excluding athletic)", ? "Clothing accessories (belts and so on)" ) x x1 <- str_replace(x, ? "Clothing and footwear", ? "Clothing and shoes" ) x1 x2 <- str_replace(x, ? "Women's clothing", ? "Women's clothing goods" ) x2 x3 <- str_replace(x, ? "Clothing accessories (belts and so on)", ? "Clothing accessories") x3 x4 <- str_replace(x, ? "Women's footwear (excluding athletic)", ? "Women's footwear") x4
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