Join and Split
str_c(..., sep = "", collapse = NULL) Join
multiple strings into a single string.
str_c(letters, LETTERS)
str_c(..., sep = "", collapse = NULL) Collapse a
vector of strings into a single string.
str_c(letters, collapse = "")
str_dup(string, times) Repeat strings times
times. str_dup(fruit, times = 2)
str_split_fixed(string, pattern, n) Split a
vector of strings into a matrix of substrings
(splitting at occurrences of a pattern match).
Also str_split to return a list of substrings.
str_split_fixed(fruit, " ", n=2)
glue::glue(..., .sep = "", .envir =
parent.frame(), .open = "{", .close = "}") Create
a string from strings and {expressions} to
evaluate. glue::glue("Pi is {pi}")
glue::glue_data(.x, ..., .sep = "", .envir =
parent.frame(), .open = "{", .close = "}") Use a
data frame, list, or environment to create a
string from strings and {expressions} to
evaluate. glue::glue_data(mtcars,
"{rownames(mtcars)} has {hp} hp")
{xx}
{yy}
a string
A STRING
A STRING
a string
Mutate Strings
str_sub() <- value. Replace substrings by
identifying the substrings with str_sub() and
assigning into the results.
str_sub(fruit, 1, 3) <- "str"
str_replace(string, pattern, replacement)
Replace the first matched pattern in each
string. str_replace(fruit, "a", "-")
str_replace_all(string, pattern,
replacement) Replace all matched patterns
in each string. str_replace_all(fruit, "a", "-")
str_to_lower(string, locale = "en")
1
Convert
strings to lower case.
str_to_lower(sentences)
str_to_upper(string, locale = "en")
1
Convert
strings to upper case.
str_to_upper(sentences)
str_to_title(string, locale = "en")
1
Convert
strings to title case. str_to_title(sentences)
a string
A String
str_conv(string, encoding) Override the
encoding of a string. str_conv(fruit,"ISO-8859-1")
str_view(string, pattern, match = NA) View
HTML rendering of first regex match in each
string. str_view(fruit, "[aeiou]")
str_view_all(string, pattern, match = NA) View
HTML rendering of all regex matches.
str_view_all(fruit, "[aeiou]")
str_wrap(string, width = 80, indent = 0, exdent
= 0) Wrap strings into nicely formatted
paragraphs. str_wrap(sentences, 20)
RStudio® is a trademark of RStudio, Inc. • CC BY SA RStudio • info@rstudio.com • 844-448-1212 • rstudio.com • Learn more at stringr.tidyverse.org • Diagrams from @LVaudor ! • stringr 1.2.0 • Updated: 2017-10
Work with strings with stringr : : CHEAT SHEET
Detect Matches
str_detect(string, pattern) Detect the
presence of a pattern match in a string.
str_detect(fruit, "a")
str_which(string, pattern) Find the indexes of
strings that contain a pattern match.
str_which(fruit, "a")
str_count(string, pattern) Count the number
of matches in a string.
str_count(fruit, "a")
str_locate(string, pattern) Locate the
positions of pattern matches in a string. Also
str_locate_all. str_locate(fruit, "a")
Manage Lengths
TRUE
TRUE
FALSE
TRUE
1
2
4
0
3
1
2
start
end
2
4
4
7
NA
NA
3
4
str_length(string) The width of strings (i.e.
number of code points, which generally equals
the number of characters). str_length(fruit)
str_pad(string, width, side = c("le", "right",
"both"), pad = " ") Pad strings to constant
width. str_pad(fruit, 17)
str_trunc(string, width, side = c("right", "le",
"center"), ellipsis = "...") Truncate the width of
strings, replacing content with ellipsis.
str_trunc(fruit, 3)
str_trim(string, side = c("both", "le", "right"))
Trim whitespace from the start and/or end of a
string. str_trim(fruit)
4
6
2
3
Helpers
str_order(x, decreasing = FALSE, na_last =
TRUE, locale = "en", numeric = FALSE, ...)
1
Return
the vector of indexes that sorts a character
vector. x[str_order(x)]
str_sort(x, decreasing = FALSE, na_last = TRUE,
locale = "en", numeric = FALSE, ...)
1
Sort a
character vector.
str_sort(x)
4
1
3
2
Order Strings
The stringr package provides a set of internally consistent tools for working with character strings, i.e. sequences of characters surrounded by quotation marks.
NA
NA
Subset Strings
str_sub(string, start = 1L, end = -1L) Extract
substrings from a character vector.
str_sub(fruit, 1, 3); str_sub(fruit, -2)
str_subset(string, pattern) Return only the
strings that contain a pattern match.
str_subset(fruit, "b")
str_extract(string, pattern) Return the first
pattern match found in each string, as a vector.
Also str_extract_all to return every pattern
match. str_extract(fruit, "[aeiou]")
str_match(string, pattern) Return the first
pattern match found in each string, as a
matrix with a column for each ( ) group in
pattern. Also str_match_all.
str_match(sentences, "(a|the) ([^ ]+)")
NA
1
See bit.ly/ISO639-1 for a complete list of locales.
2
...
1
n
n
...
m
regexp
matches
example
a?
zero or one
quant("a?")
.a.aa.aaa
a*
zero or more
quant("a*")
.a.aa.aaa
a+
one or more
quant("a+")
.a.aa.aaa
a{n}
exactly n
quant("a{2}")
.a.aa.aaa
a{n, }
n or more
quant("a{2,}")
.a.aa.aaa
a{n, m}
between n and m
quant("a{2,4}")
.a.aa.aaa
string
(type this)
regexp
(to mean this)
matches
(which matches this)
example
(the result is the same as ref("abba"))
\\1
\1 (etc.)
first () group, etc.
ref("(a)(b)\\2\\1")
abbaab
regexp
matches
example
^a
start of string
anchor("^a")
aaa
a$
end of string
anchor("a$")
aaa
regexp
matches
example
ab|d
or
alt("ab|d")
abcde
[abe]
one of
alt("[abe]")
abcde
[^abe]
anything but
alt("[^abe]")
abcde
[a-c]
range
alt("[a-c]")
abcde
regex(pattern, ignore_case = FALSE, multiline =
FALSE, comments = FALSE, dotall = FALSE, ...)
Modifies a regex to ignore cases, match end of
lines as well of end of strings, allow R comments
within regex's , and/or to have . match everything
including \n.
str_detect("I", regex("i", TRUE))
fixed() Matches raw bytes but will miss some
characters that can be represented in multiple
ways (fast). str_detect("\u0130", fixed("i"))
coll() Matches raw bytes and will use locale
specific collation rules to recognize characters
that can be represented in multiple ways (slow).
str_detect("\u0130", coll("i", TRUE, locale = "tr"))
boundary() Matches boundaries between
characters, line_breaks, sentences, or words.
str_split(sentences, boundary("word"))
Special Character
Represents
\\
\
\"
"
\n
new line
Need to Know Regular Expressions -
Pattern arguments in stringr are interpreted as
regular expressions aer any special characters
have been parsed.
In R, you write regular expressions as strings,
sequences of characters surrounded by quotes
("") or single quotes('').
Some characters cannot be represented directly
in an R string . These must be represented as
special characters, sequences of characters that
have a specific meaning., e.g.
RStudio® is a trademark of RStudio, Inc. • CC BY SA RStudio • info@rstudio.com • 844-448-1212 • rstudio.com • Learn more at stringr.tidyverse.org • Diagrams from @LVaudor ! • stringr 1.2.0 • Updated: 2017-10
Run ?"'" to see a complete list
Because of this, whenever a \ appears in a regular
expression, you must write it as \\ in the string
that represents the regular expression.
Use writeLines() to see how R views your string
aer all special characters have been parsed.
writeLines("\\.")
# \.
writeLines("\\ is a backslash")
# \ is a backslash
MATCH CHARACTERS
quant <- function(rx) str_view_all(".a.aa.aaa", rx)
QUANTIFIERS
anchor <- function(rx) str_view_all("aaa", rx)
ANCHORS
GROUPS
Use parentheses to set precedent (order of evaluation) and create groups
Use an escaped number to refer to and duplicate parentheses groups that occur
earlier in a pattern. Refer to each group by its order of appearance
ref <- function(rx) str_view_all("abbaab", rx)
alt <- function(rx) str_view_all("abcde", rx)
ALTERNATES
look <- function(rx) str_view_all("bacad", rx)
LOOK AROUNDS
INTERPRETATION
Patterns in stringr are interpreted as regexs To
change this default, wrap the pattern in one of:
regexp
matches
example
(ab|d)e
sets precedence
alt("(ab|d)e")
abcde
see <- function(rx) str_view_all("abc ABC 123\t.!?\\(){}\n", rx)
Regular expressions, or regexps, are a concise language for
describing patterns in strings.
a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
p
q
r
s
t
u
v
w
x
z
[:lower:]
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Z
[:upper:]
[:alpha:]
0
1
2
3
4
5
6
7
8
9
[:digit:]
[:alnum:]
[:punct:]
.
,
:
;
?
!
\
|
/
`
=
*
+
-
^
_
~
"
'
[
]
{
}
(
)
<
>
@
#
$
[:graph:]
.
[:blank:]
[:space:]
space
tab
new line
"
1
Many base R functions require classes to be wrapped in a second set of [ ], e.g. [[:digit:]]
string (type
this)
regexp
(to mean this)
matches
(which matches this)
example
a (etc.)
a (etc.)
see("a")
abc ABC 123 .!?\(){}
\\.
\.
.
see("\\.")
abc ABC 123 .!?\(){}
\\!
\!
!
see("\\!")
abc ABC 123 .!?\(){}
\\?
\?
?
see("\\?")
abc ABC 123 .!?\(){}
\\\\
\\
\
see("\\\\")
abc ABC 123 .!?\(){}
\\(
\(
(
see("\\(")
abc ABC 123 .!?\(){}
\\)
\)
)
see("\\)")
abc ABC 123 .!?\(){}
\\{
\{
{
see("\\{")
abc ABC 123 .!?\(){}
\\}
\}
}
see( "\\}")
abc ABC 123 .!?\(){}
\\n
\n
new line (return)
see("\\n")
abc ABC 123 .!?\(){}
\\t
\t
tab
see("\\t")
abc ABC 123 .!?\(){}
\\s
\s
any whitespace (\S for non-whitespaces)
see("\\s")
abc ABC 123 .!?\(){}
\\d
\d
any digit (\D for non-digits)
see("\\d")
abc ABC 123 .!?\(){}
\\w
\w
any word character (\W for non-word chars)
see("\\w")
abc ABC 123 .!?\(){}
\\b
\b
word boundaries
see("\\b")
abc ABC 123 .!?\(){}
[:digit:]
digits
see("[:digit:]")
abc ABC 123 .!?\(){}
[:alpha:]
letters
see("[:alpha:]")
abc ABC 123 .!?\(){}
[:lower:]
lowercase letters
see("[:lower:]")
abc ABC 123 .!?\(){}
[:upper:]
uppercase letters
see("[:upper:]")
abc ABC 123 .!?\(){}
[:alnum:]
letters and numbers
see("[:alnum:]")
abc ABC 123 .!?\(){}
[:punct:]
punctuation
see("[:punct:]")
abc ABC 123 .!?\(){}
[:graph:]
letters, numbers, and punctuation
see("[:graph:]")
abc ABC 123 .!?\(){}
[:space:]
space characters (i.e. \s)
see("[:space:]")
abc ABC 123 .!?\(){}
[:blank:]
space and tab (but not new line)
see("[:blank:]")
abc ABC 123 .!?\(){}
.
every character except a new line
see(".")
abc ABC 123 .!?\(){}
1
1
1
1
1
1
1
1
1
1
2
...
n
regexp
matches
example
a(?=c)
followed by
look("a(?=c)")
bacad
a(?!c)
not followed by
look("a(?!c)")
bacad
(?<=b)a
preceded by
look("(?<=b)a")
bacad
(?<!b)a
not preceded by
look("(?<!b)a")
bacad
