[R] Problem with the str_replace function

[phii m@iii@g oii phiiipsmith@c@]

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, phil using 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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