Your help is much appreciated. I now understand what my problem was and
can move forward.
Philip
On 2021-03-17 01:19, Hervé Pagès wrote:
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, p...@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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