String functions
Learn how to use and combine different string functions in APL
String functions
Function Name | Description |
---|---|
base64_encode_tostring() | Encodes a string as base64 string. |
base64_decode_tostring() | Decodes a base64 string to a UTF-8 string. |
countof() | Counts occurrences of a substring in a string. |
countof_regex() | Counts occurrences of a substring in a string. Regex matches don’t. |
coalesce() | Evaluates a list of expressions and returns the first non-null (or non-empty for string) expression. |
extract() | Get a match for a regular expression from a text string. |
extract_all() | Get all matches for a regular expression from a text string. |
format_bytes() | Formats a number of bytes as a string including bytes units |
format_url() | Formats an input string into a valid URL by adding the necessary protocol if it’s escaping illegal URL characters. |
indexof() | Function reports the zero-based index of the first occurrence of a specified string within input string. |
isempty() | Returns true if the argument is an empty string or is null. |
isnotempty() | Returns true if the argument isn’t an empty string or a null. |
isnotnull() | Returns true if the argument is not null. |
isnull() | Evaluates its sole argument and returns a bool value indicating if the argument evaluates to a null value. |
parse_bytes() | Parses a string including byte size units and returns the number of bytes |
parse_json() | Interprets a string as a JSON value) and returns the value as dynamic. |
parse_url() | Parses an absolute URL string and returns a dynamic object contains all parts of the URL. |
parse_urlquery() | Parses a url query string and returns a dynamic object contains the Query parameters. |
replace() | Replace all regex matches with another string. |
replace_regex() | Replaces all regex matches with another string. |
replace_string() | Replaces all string matches with another string. |
reverse() | Function makes reverse of input string. |
split() | Splits a given string according to a given delimiter and returns a string array with the contained substrings. |
strcat() | Concatenates between 1 and 64 arguments. |
strcat_delim() | Concatenates between 2 and 64 arguments, with delimiter, provided as first argument. |
strcmp() | Compares two strings. |
strlen() | Returns the length, in characters, of the input string. |
strrep() | Repeats given string provided number of times (default = 1). |
substring() | Extracts a substring from a source string starting from some index to the end of the string. |
toupper() | Converts a string to upper case. |
tolower() | Converts a string to lower case. |
trim() | Removes all leading and trailing matches of the specified cutset. |
trim_regex() | Removes all leading and trailing matches of the specified regular expression. |
trim_end() | Removes trailing match of the specified cutset. |
trim_end_regex() | Removes trailing match of the specified regular expression. |
trim_start() | Removes leading match of the specified cutset. |
trim_start_regex() | Removes leading match of the specified regular expression. |
url_decode() | The function converts encoded URL into a regular URL representation. |
url_encode() | The function converts characters of the input URL into a format that can be transmitted over the Internet. |
gettype() | Returns the runtime type of its single argument. |
parse_csv() | Splits a given string representing a single record of comma-separated values and returns a string array with these values. |
Each argument has a required section which is denoted with required
or optional
- If it’s denoted by
required
it means the argument must be passed into that function before it’ll work. - if it’s denoted by
optional
it means the function can work without passing the argument value.
base64_encode_tostring()
Encodes a string as base64 string.
Arguments
Name | Type | Required or Optional | Description |
---|---|---|---|
String | string | Required | Input string or string field to be encoded as base64 string. |
Returns
Returns the string encoded as base64 string.
- To decode base64 strings to UTF-8 strings, see base64_decode_tostring()
Examples
base64_encode_tostring(string)
['sample-http-logs']
| project encoded_base64_string = base64_encode_tostring(content_type)
base64_decode_tostring()
Decodes a base64 string to a UTF-8 string.
Arguments
Name | Type | Required or Optional | Description |
---|---|---|---|
String | string | Required | Input string or string field to be decoded from base64 to UTF8-8 string. |
Returns
Returns UTF-8 string decoded from base64 string.
- To encode strings to base64 string, see base64_encode_tostring()
Examples
base64_decode_tostring(string)
['sample-http-logs']
| project decoded_base64_string = base64_decode_tostring("VGhpcyBpcyBhbiBlbmNvZGVkIG1lc3NhZ2Uu")
countof()
Counts occurrences of a substring in a string.
Arguments
name | type | description | Required or Optional |
---|---|---|---|
text source | string | Source to count your occurences from | Required |
search | string | The plain string to match inside source. | Required |
Returns
The number of times that the search string can be matched.
Examples
countof(search, text)
['sample-http-logs']
| project count = countof("con", "content_type")
countof_regex()
Counts occurrences of a substring in a string. regex matches don’t.
Arguments
- text source: A string.
- regex search: regular expression to match inside your text source.
Returns
The number of times that the search string can be matched in the dataset. Regex matches do not.
Examples
countof_regex(regex, text)
['sample-http-logs']
| project count = countof_regex("c.n", "content_type")
coalesce()
Evaluates a list of expressions and returns the first non-null (or non-empty for string) expression.
Arguments
name | type | description | Required or Optional |
---|---|---|---|
arguments | scalar | The expression or field to be evaluated. | Required |
Returns
The value of the first argument whose value isn’t null (or not-empty for string expressions).
Examples
['sample-http-logs']
| project coalesced = coalesce(content_type, ['geo.city'], method)
['http-logs']
| project req_duration_ms, server_datacenter, predicate = coalesce(content_type, method, status)
extract()
Convert the extracted substring to the indicated type.
Arguments
name | type | description |
---|---|---|
regex | expression | A regular expression. |
captureGroup | int | A positive int constant indicating the capture group to extract. 0 stands for the entire match, 1 for the value matched by the first ’(‘parenthesis’)’ in the regular expression, 2 or more for subsequent parentheses. |
source | string | A string to search |
Returns
If regex finds a match in source: the substring matched against the indicated capture group captureGroup, optionally converted to typeLiteral.
If there’s no match, or the type conversion fails: -1
or string error
Examples
extract(regex, captureGroup, source)
['sample-http-logs']
| project extract_sub = extract("^.{2,2}(.{4,4})", 1, content_type)
extract("x=([0-9.]+)", 1, "axiom x=65.6|po") == "65.6"
extract_all()
retrieve a subset of matching groups.
Arguments
name | type | description | Required or Optional |
---|---|---|---|
regex | expression | A regular expression containing between one and 16 capture groups. Examples of a valid regex: @”(\d+)“. Examples of an invalid regex: @“\d+” | Required |
captureGroups | array | A dynamic array constant that indicates the capture group to extract. Valid values are from 1 to the number of capturing groups in the regular expression. | optional |
source | string | A string to search | Required |
Returns
- If regex finds a match in source: Returns dynamic array including all matches against the indicated capture groups captureGroups, or all of capturing groups in the regex.
- If number of captureGroups is 1: The returned array has a single dimension of matched values.
- If number of captureGroups is more than 1: The returned array is a two-dimensional collection of multi-value matches per captureGroups selection, or all capture groups present in the regex if captureGroups is omitted.
- If there’s no match:
-1
Examples
extract_all(regex, [captureGroups,] source)
['sample-http-logs']
| project extract_match = extract_all(@"(\w)(\w+)(\w)", dynamic([1,3]), content_type)
extract_all(@"(\w)(\w+)(\w)", dynamic([1,3]), content_type) == [["t", "t"],["c","v"]]
format_bytes()
Formats a number as a string representing data size in bytes.
Arguments
name | type | description | Required or Optional |
---|---|---|---|
value | number | a number to be formatted as data size in bytes | Required |
precision | number | Number of digits the value will be rounded to. (default value is zero) | Optional |
units | string | Units of the target data size the string formatting will use (base 2 suffixes: Bytes , KiB , KB , MiB , MB , GiB , GB , TiB , TB , PiB , EiB , ZiB , YiB ; base 10 suffixes: kB MB GB TB PB EB ZB YB ). If the parameter is empty the units will be auto-selected based on input value. | Optional |
base | number | Either 2 or 10 to specify whether the prefix is calculated using 1000s or 1024s for each type. (default value is 2) | Optional |
Returns
- A formatted string for humans
Examples
format_bytes( 4000, number, "['id']", num_comments ) == "3.9062500000000 KB"
format_bytes(value [, precision [, units [, base]]])
format_bytes(1024) == "1 KB"
format_bytes(8000000, 2, "MB", 10) == "8.00 MB"
['github-issues-event']
| project formated_bytes = format_bytes( 4783549035, number, "['id']", num_comments )
format_url()
Formats an input string into a valid URL. This function will return a string that is a properly formatted URL.
Arguments
name | type | description | Required or Optional |
---|---|---|---|
url | dynamic | string input you want to format into a URL | Required |
Returns
- A string that represents a properly formatted URL.
Examples
['sample-http-logs']
| project formatted_url = format_url(dynamic({"scheme": "https", "host": "github.com", "path": "/axiomhq/next-axiom"})
['sample-http-logs']
| project formatted_url = format_url(dynamic({"scheme": "https", "host": "github.com", "path": "/axiomhq/next-axiom", "port": 443, "fragment": "axiom","user": "axiom", "password": "apl"}))
- These are all the supported keys when using the
format_url
function: scheme, host, port, fragment, user, password, query.
indexof()
Reports the zero-based index of the first occurrence of a specified string within the input string.
Arguments
name | type | description | usage |
---|---|---|---|
source | string | Input string | Required |
lookup | string | String to look up | Required |
start_index | text | Search start position. | Optional |
length | characters | Number of character positions to examine. A value of -1 means unlimited length. | Optional |
occurrence | number | The number of the occurrence. Default 1. | Optional |
Returns
-
Zero-based index position of lookup.
-
Returns -1 if the string isn’t found in the input.
Examples
indexof( body, ['id'], 2, 1, number ) == "-1"
indexof(source,lookup[,start_index[,length[,occurrence]]])
indexof ()
['github-issues-event']
| project occurrence = indexof( body, ['id'], 23, 5, number )
isempty()
Returns true
if the argument is an empty string or is null.
Returns
Indicates whether the argument is an empty string or isnull.
Examples
isempty("") == true
isempty([value])
['github-issues-event']
| project empty = isempty(num_comments)
isnotempty()
Returns true
if the argument isn’t an empty string, and it isn’t null.
Examples
isnotempty("") == false
isnotempty([value])
notempty([value]) -- alias of isnotempty
['github-issues-event']
| project not_empty = isnotempty(num_comments)
isnotnull()
Returns true
if the argument is not null.
Examples
isnotnull( num_comments ) == true
isnotnull([value])
notnull([value]) - alias for `isnotnull`
['github-issues-event']
| project not_null = isnotnull(num_comments)
isnull()
Evaluates its sole argument and returns a bool value indicating if the argument evaluates to a null value.
Returns
True or false, depending on whether or not the value is null.
Examples
isnull(Expr)
['github-issues-event']
| project is_null = isnull(creator)
parse_bytes()
Parses a string including byte size units and returns the number of bytes
Arguments
name | type | description | Required or Optional |
---|---|---|---|
bytes_string | string | A string formated defining the number of bytes | Required |
base | number | (optional) Either 2 or 10 to specify whether the prefix is calculated using 1000s or 1024s for each type. (default value is 2) | Required |
Returns
- The number of bytes or zero if unable to parse
Examples
parse_bytes(bytes_string [, base])
parse_bytes("1 KB") == 1024
parse_bytes("1 KB", 10) == 1000
parse_bytes("128 Bytes") == 128
parse_bytes("bad data") == 0
['github-issues-event']
| extend parsed_bytes = parse_bytes("300 KB", 10)
['github-issues-event']
| project parsed_bytes = parse_bytes("300 KB", 10)
parse_json()
Interprets a string as a JSON value and returns the value as dynamic.
Arguments
Name | Type | Required or Optional | Description |
---|---|---|---|
Json Expr | string | Required | Expression that will be used, also represents a JSON-formatted value |
Returns
An object of type json that is determined by the value of json:
-
If json is of type string, and is a properly formatted JSON string, then the string is parsed, and the value produced is returned.
-
If json is of type string, but it isn’t a properly formatted JSON string, then the returned value is an object of type dynamic that holds the original string value.
Examples
parse_json(json)
['vercel']
| extend parsed = parse_json('{"name":"vercel", "statuscode":200, "region": { "route": "usage streams", "number": 9 }}')
['github-issues-event']
| extend parsed = parse_json(creator)
| where isnotnull( parsed)
parse_url()
Parses an absolute URL string
and returns an object contains URL parts.
Arguments
Name | Type | Required or Optional | Description |
---|---|---|---|
URL | string | Required | A string represents a URL or the query part of the URL. |
Returns
An object of type dynamic that included the URL components: Scheme, Host, Port, Path, Username, Password, Query Parameters, Fragment.
Examples
parse_url(url)
['sample-http-logs']
| extend ParsedURL = parse_url("https://www.example.com/path/to/page?query=example")
| project
Scheme = ParsedURL["scheme"],
Host = ParsedURL["host"],
Path = ParsedURL["path"],
Query = ParsedURL["query"]
- Result
{
"Host": "www.example.com",
"Path": "/path/to/page",
"Query": {
"query": "example"
},
"Scheme": "https"
}
parse_urlquery()
Returns a dynamic
object contains the Query parameters.
Arguments
Name | Type | Required or Optional | Description |
---|---|---|---|
Query | string | Required | A string represents a url query. |
query: A string represents a url query
Returns
An object of type dynamic that includes the query parameters.
Examples
parse_urlquery("a1=b1&a2=b2&a3=b3")
- Result
{
"Result": {
"a3": "b3",
"a2": "b2",
"a1": "b1"
}
}
parse_urlquery(query)
['github-issues-event']
| project parsed = parse_urlquery("https://play.axiom.co/axiom-play-qf1k/explorer?qid=fUKgiQgLjKE-rd7wjy")
replace()
Replace all regex matches with another string.
Arguments
- regex: The regular expression to search source. It can contain capture groups in ’(‘parentheses’)‘.
- rewrite: The replacement regex for any match made by matchingRegex. Use 1 for the first capture group, $2 and so on for subsequent capture groups.
- source: A string.
Returns
- source after replacing all matches of regex with evaluations of rewrite. Matches do not overlap.
Examples
replace(regex, rewrite, source)
['sample-http-logs']
| project content_type, Comment = replace("[html]", "[censored]", method)
replace_regex()
Replaces all regex matches with another string.
Arguments
- regex: The regular expression to search text.
- rewrite: The replacement regex for any match made by matchingRegex.
- text: A string.
Returns
source after replacing all matches of regex with evaluations of rewrite. Matches do not overlap.
Examples
replace_regex(@'^logging', 'axiom', 'logging-data')
- Result
{
"replaced": "axiom-data"
}
replace_regex(regex, rewrite, text)
['github-issues-event']
| extend replaced = replace_regex(@'^logging', 'axiom', 'logging-data')
Backreferences
Backreferences match the same text as previously matched by a capturing group. With Backreferences, you can identify a repeated character or substring within a string.
- Backreferences in APL is implemented using the
$
sign.
Examples
['github-issues-event']
| project backreferences = replace_regex(@'observability=(\d+)', 'axiom=$1', creator)
replace_string()
Replaces all string matches with another string.
Arguments
Name | Type | Required or Optional | Description |
---|---|---|---|
text | string | Required | A string |
lookup | string | Required | A string to be replaced. |
reqrite | string | Required | A replacement string. |
Returns
text after replacing all matches of lookup with evaluations of rewrite. Matches do not overlap.
Examples
replace_string( "creator", "github", "axiom" )
- Result
{
"replaced_string": "axiom"
}
replace_string(text, lookup, rewrite)
['github-issues-event']
| extend replaced_string = replace_string( "creator", "github", "replace" )
reverse()
Function reverses the order of the input Field.
Arguments
name | type | description | Required or Optional |
---|---|---|---|
Field | string | Field input value | Required |
Returns
The reverse order of a field value.
Examples
reverse(value)
project reversed = reverse("axiom")
- Result
moixa
split()
Splits a given string according to a given delimiter and returns a string array with the contained substrings.
Optionally, a specific substring can be returned if exists.
Arguments
- source: The source string that will be split according to the given delimiter.
- delimiter: The delimiter (Field) that will be used in order to split the source string.
Returns
- A string array that contains the substrings of the given source string that are delimited by the given delimiter.
Examples
split(source, delimiter)
project split_str = split("axiom_observability_monitoring", "_")
- Result
{
"split_str": ["axiom", "observability", "monitoring"]
}
strcat()
Concatenates between 1 and 64 arguments.
If the arguments aren’t of string type, they’ll be forcibly converted to string.
Arguments
Name | Type | Required or Optional | Description |
---|---|---|---|
Expr | string | Required | Expressions to be concatenated. |
Returns
Arguments, concatenated to a single string.
Examples
strcat(argument1, argument2[, argumentN])
['github-issues-event']
| project stract_con = strcat( ['milestone.creator'], number )
['github-issues-event']
| project stract_con = strcat( 'axiom', number )
- Result
{
"stract_con": "axiom3249"
}
strcat_delim()
Concatenates between 2 and 64 arguments, with delimiter, provided as first argument.
- If arguments aren’t of string type, they’ll be forcibly converted to string.
Arguments
Name | Type | Required or Optional | Description |
---|---|---|---|
delimiter | string | Required | string expression, which will be used as separator. |
argument1 .. | string | Required | Expressions to be concatenated. |
Returns
Arguments, concatenated to a single string with delimiter.
Examples
strcat_delim(delimiter, argument1, argument2[ , argumentN])
['github-issues-event']
| project strcat = strcat_delim(":", actor, creator)
project strcat = strcat_delim(":", "axiom", "monitoring")
- Result
{
"strcat": "axiom:monitoring"
}
strcmp()
Compares two strings.
The function starts comparing the first character of each string. If they are equal to each other, it continues with the following pairs until the characters differ or until the end of shorter string is reached.
Arguments
Name | Type | Required or Optional | Description |
---|---|---|---|
string1 | string | Required | first input string for comparison. |
string2 | string | Required | second input string for comparison. |
Returns
Returns an integral value indicating the relationship between the strings:
- When the result is 0: The contents of both strings are equal.
- When the result is -1: the first character that does not match has a lower value in string1 than in string2.
- When the result is 1: the first character that does not match has a higher value in string1 than in string2.
Examples
strcmp(string1, string2)
['github-issues-event']
| extend cmp = strcmp( body, repo )
project cmp = strcmp( "axiom", "observability")
- Result
{
"input_string": -1
}
strlen()
Returns the length, in characters, of the input string.
Arguments
Name | Type | Required or Optional | Description |
---|---|---|---|
source | string | Required | The source string that will be measured for string length. |
Returns
Returns the length, in characters, of the input string.
Examples
strlen(source)
project str_len = strlen("axiom")
- Result
{
"str_len": 5
}
strrep()
Repeats given string provided amount of times.
- In case if first or third argument is not of a string type, it will be forcibly converted to string.
Arguments
Name | Type | Required or Optional | Description |
---|---|---|---|
value | Expr | Required | Inpute Expression |
multiplier | integer | Required | positive integer value (from 1 to 1024) |
delimiter | string | Optional | An optional string expression (default: empty string) |
Returns
-
Value repeated for a specified number of times, concatenated with delimiter.
-
In case if multiplier is more than maximal allowed value (1024), input string will be repeated 1024 times.
Examples
strrep(value,multiplier,[delimiter])
['github-issues-event']
| extend repeat_string = strrep( repo, 5, "::" )
project repeat_string = strrep( "axiom", 3, "::" )
- Result
{
"repeat_string": "axiom::axiom::axiom"
}
substring()
Extracts a substring from a source string starting from some index to the end of the string.
Arguments
- source: The source string that the substring will be taken from.
- startingIndex: The zero-based starting character position of the requested substring.
- length: A parameter that can be used to specify the requested number of characters in the substring.
Returns
A substring from the given string. The substring starts at startingIndex (zero-based) character position and continues to the end of the string or length characters if specified.
Examples
substring(source, startingIndex [, length])
['github-issues-event']
| extend extract_string = substring( repo, 4, 5 )
project extract_string = substring( "axiom", 4, 5 )
{
"extract_string": "m"
}
toupper()
Converts a string to upper case.
toupper("axiom") == "AXIOM"
['github-issues-event']
| project upper = toupper( body )
tolower()
Converts a string to lower case.
tolower("AXIOM") == "axiom"
['github-issues-event']
| project low = tolower( body )
trim()
Removes all leading and trailing matches of the specified cutset.
Arguments
- source: A string.
- cutset: A string containing the characters to be removed.
Returns
source after trimming matches of the cutset found in the beginning and/or the end of source.
Examples
trim(source)
['github-issues-event']
| extend remove_leading_matches = trim( "locked", repo)
project remove_leading_matches = trim( "axiom", "observability")
- Result
{
"remove_leading_matches": "bservability"
}
trim_regex()
Removes all leading and trailing matches of the specified regular expression.
Arguments
- regex: String or regular expression to be trimmed from the beginning and/or the end of source.
- source: A string.
Returns
source after trimming matches of regex found in the beginning and/or the end of source.
Examples
trim_regex(regex, source)
['github-issues-event']
| extend remove_trailing_match_regex = trim_regex( "^github", action )
- Result
{
"remove_trailing_match_regex": "closed"
}
trim_end()
Removes trailing match of the specified cutset.
Arguments
- source: A string.
- cutset: A string containing the characters to be removed.`
Returns
source after trimming matches of the cutset found in the end of source.
Examples
trim_end(source)
['github-issues-event']
| extend remove_cutset = trim_end(@"[^\w]+", body)
- Result
{
"remove_cutset": "In [`9128d50`](https://7aa98788e07\n), **down**:\n- HTTP code: 0\n- Response time: 0 ms\n"
}
trim_end_regex()
Removes trailing match of the specified regular expression.
Arguments
- regex: String or regular expression to be trimmed from the end of source.
- source: A string.
Returns
source after trimming matches of regex found in the end of source.
Examples
trim_end_regex(regex, source)
['github-issues-event']
| project remove_cutset_regex = trim_end_regex( "^github", creator )
- Result
{
"remove_cutset_regex": "axiomhq"
}
trim_start()
Removes leading match of the specified cutset.
Arguments
- source: A string.
Returns
- source after trimming match of the specified cutset found in the beginning of source.
Examples
trim_start(source)
['github-issues-event']
| project remove_cutset = trim_start( "github", repo)
- Result
{
"remove_cutset": "axiomhq/next-axiom"
}
trim_start_regex()
Removes leading match of the specified regular expression.
Arguments
- regex: String or regular expression to be trimmed from the beginning of source.
- source: A string.
Returns
source after trimming match of regex found in the beginning of source.
Examples
trim_start_regex(regex, source)
['github-issues-event']
| project remove_cutset = trim_start_regex( "github", repo)
- Result
{
"remove_cutset": "axiomhq/next-axiom"
}
url_decode()
The function converts encoded URL into a to regular URL representation.
Arguments
encoded url:
encoded URL (string).
Returns
URL (string) in a regular representation.
Examples
url_decode(encoded url)
['github-issues-event']
| project decoded_link = url_decode( "https://www.axiom.co/" )
- Result
{
"decoded_link": "https://www.axiom.co/"
}
url_encode()
The function converts characters of the input URL into a format that can be transmitted over the Internet.
Arguments
- url: input URL (string).
Returns
URL (string) converted into a format that can be transmitted over the Internet.
Examples
url_encode(url)
['github-issues-event']
| project encoded_url = url_encode( "https://www.axiom.co/" )
- Result
{
"encoded_link": "https%3A%2F%2Fwww.axiom.co%2F"
}
gettype()
Returns the runtime type of its single argument.
Arguments
- Expressions
Returns
A string representing the runtime type of its single argument.
Examples
Expression | Returns |
---|---|
gettype(“lima”) | string |
gettype(2222) | int |
gettype(5==5) | bool |
gettype(now()) | datetime |
gettype(parse_json(‘67’)) | int |
gettype(parse_json(’ “polish” ‘)) | string |
gettype(parse_json(’ {“axiom”:1234} ‘)) | dictionary |
gettype(parse_json(’ [6, 7, 8] ‘)) | array |
gettype(456.98) | real |
gettype(parse_json(”)) | null |
parse_csv()
Splits a given string representing a single record of comma-separated values and returns a string array with these values.
Arguments
- csv_text: A string representing a single record of comma-separated values.
Returns
A string array that contains the split values.
Examples
parse_csv("axiom,logging,observability") == [ "axiom", "logging", "observability" ]
parse_csv("axiom, processing, language") == [ "axiom", "processing", "language" ]
['github-issues-event']
| project parse_csv("github, body, repo")