Struct Metadata 

pub struct Metadata {
    pub keywords: KeywordMap,
    pub delimiter: char,
}

Contains keyword-value pairs and delimiter from the TEXT segment of an FCS file

The TEXT segment contains all metadata about the FCS file, including:

• File information (GUID, filename, cytometer type)
• Data structure information (number of events, parameters, data type, byte order)
• Parameter metadata (names, labels, ranges, transforms)
• Optional information (compensation matrices, timestamps, etc.)

Keywords are stored in a hashmap for fast lookup, with type-safe accessors for different keyword types (integer, float, string, byte, mixed).

Fields

keywords: KeywordMap

delimiter: char

Implementations

impl Metadata

pub fn new() -> Self

pub fn print_sorted_by_keyword(&self)

Prints all keywords sorted alphabetically by key name

This is a debugging utility that displays all keyword-value pairs in the metadata, sorted for easy reading.

pub fn from_mmap(mmap: &Mmap, header: &Header) -> Self

Reads the text segment of the fcs file and returns an Metadata struct

Uses memchr for fast delimiter finding (5-10x faster than byte-by-byte iteration)

pub fn validate_text_segment_keywords(&self, header: &Header) -> Result<()>

Check that required keys are present in the TEXT segment of the metadata

Errors

Will return Err if:

• any of the required keywords are missing from the keywords hashmap
• the number of parameters can’t be obtained from the $PAR keyword in the TEXT section
• any keyword has a Pn[X] value where n is greater than the number of parameters indicated by the $PAR keyword

pub fn validate_guid(&mut self)

Validates if a GUID is present in the file’s metadata, and if not, generates a new one.

pub fn get_number_of_parameters(&self) -> Result<&usize>

Return the number of parameters in the file from the $PAR keyword in the metadata TEXT section

Errors

Will return Err if the $PAR keyword is not present in the metadata keywords hashmap

pub fn get_number_of_events(&self) -> Result<&usize>

Return the number of events in the file from the $TOT keyword in the metadata TEXT section

Errors

Will return Err if the $TOT keyword is not present in the metadata keywords hashmap

pub fn get_data_type(&self) -> Result<&FcsDataType>

Return the data type from the $DATATYPE keyword in the metadata TEXT section, unwraps and returns it if it exists.

Errors

Will return Err if the $DATATYPE keyword is not present in the metadata keywords hashmap

pub fn get_data_type_for_channel( &self, parameter_number: usize, ) -> Result<FcsDataType>

Get the data type for a specific channel/parameter (FCS 3.2+)

First checks for $PnDATATYPE keyword to see if this parameter has a specific data type override. If not found, falls back to the default $DATATYPE keyword.

Arguments

• parameter_number - 1-based parameter index

Errors

Will return Err if neither $PnDATATYPE nor $DATATYPE is present

pub fn calculate_bytes_per_event(&self) -> Result<usize>

Calculate the total bytes per event by summing bytes per parameter

Uses $PnB (bits per parameter) divided by 8 to get bytes per parameter, then sums across all parameters. This is more accurate than using $DATATYPE which only provides a default value.

Errors

Will return Err if the number of parameters cannot be determined or if any required $PnB keyword is missing

pub fn get_bytes_per_parameter(&self, parameter_number: usize) -> Result<usize>

Get bytes per parameter for a specific channel

Uses $PnB (bits per parameter) divided by 8 to get bytes per parameter.

Arguments

• parameter_number - 1-based parameter index

Errors

Will return Err if the $PnB keyword is missing for this parameter

pub fn get_byte_order(&self) -> Result<&ByteOrder>

Return the byte order from the $BYTEORD keyword in the metadata TEXT section, unwraps and returns it if it exists.

Errors

Will return Err if the $BYTEORD keyword is not present in the keywords hashmap

pub fn get_integer_keyword(&self, keyword: &str) -> Result<&IntegerKeyword>

Returns a keyword that holds numeric data from the keywords hashmap, if it exists

Errors

Will return Err if the keyword is not present in the keywords hashmap

pub fn get_float_keyword(&self, keyword: &str) -> Result<&FloatKeyword>

Returns a keyword that holds numeric data from the keywords hashmap, if it exists

Errors

Will return Err if the keyword is not present in the keywords hashmap

pub fn get_string_keyword(&self, keyword: &str) -> Result<&StringKeyword>

Returns a keyword that holds string data from the keywords hashmap, if it exists

Errors

Will return Err if the keyword is not present in the keywords hashmap

pub fn get_byte_keyword(&self, keyword: &str) -> Result<&ByteKeyword>

Returns a keyword that holds byte-orientation data from the keywords hashmap, if it exists

Errors

Will return Err if the keyword is not present in the keywords hashmap

pub fn get_mixed_keyword(&self, keyword: &str) -> Result<&MixedKeyword>

Returns a keyword that holds mixed data from the keywords hashmap, if it exists

Errors

Will return Err if the keyword is not present in the keywords hashmap

pub fn get_parameter_string_metadata( &self, parameter_number: usize, suffix: &str, ) -> Result<&StringKeyword>

General function to get a given parameter’s string keyword from the file’s metadata (e.g. $PnN or $PnS)

Errors

Will return Err if the keyword is not present in the keywords hashmap

pub fn get_parameter_numeric_metadata( &self, parameter_number: usize, suffix: &str, ) -> Result<&IntegerKeyword>

Generic function to get a given parameter’s integer keyword from the file’s metadata (e.g. $PnN, $PnS)

Errors

Will return Err if the keyword is not present in the keywords hashmap

pub fn get_parameter_byte_metadata( &self, parameter_number: usize, suffix: &str, ) -> Result<&ByteKeyword>

Generic function to get a given parameter’s byte keyword from the file’s metadata (e.g. $PnDATATYPE)

Errors

Will return Err if the keyword is not present in the keywords hashmap

pub fn get_parameter_excitation_wavelength( &self, parameter_number: usize, ) -> Result<Option<usize>>

Get excitation wavelength(s) for a parameter from $PnL keyword Returns the first wavelength if multiple are present (for co-axial lasers)

Errors

Will return Err if the keyword is not present in the keywords hashmap

pub fn get_parameter_channel_name( &self, parameter_number: usize, ) -> Result<&str>

Return the name of the parameter’s channel from the $PnN keyword in the metadata TEXT section, where n is the provided parameter index (1-based)

Errors

Will return Err if the keyword is not present in the keywords hashmap

pub fn get_parameter_label(&self, parameter_number: usize) -> Result<&str>

Return the label name of the parameter from the $PnS keyword in the metadata TEXT section, where n is the provided parameter number

Errors

Will return Err if the keyword is not present in the keywords hashmap

pub fn get_metadata_as_json_string(&self) -> Result<String>

Transform the metadata keywords hashmap into a JSON object via serde

Errors

Will return Err if the metadata keywords hashmap is empty

pub fn insert_string_keyword(&mut self, key: String, value: String)

Insert or update a string keyword in the metadata

pub fn from_dataframe_and_parameters( df: &DataFrame, params: &ParameterMap, ) -> Result<Self>

Create metadata from a DataFrame and ParameterMap

This helper function creates all required FCS metadata keywords from scratch, including file structure keywords ($BYTEORD, $DATATYPE, $MODE, $PAR, $TOT, $NEXTDATA) and parameter-specific keywords ($PnN, $PnS, $PnB, $PnE, $PnR) for each parameter.

Arguments

• df - The DataFrame containing event data
• params - The ParameterMap containing parameter metadata

Returns

A new Metadata struct with all required keywords populated

Trait Implementations

impl Clone for Metadata

fn clone(&self) -> Metadata

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Metadata

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Metadata

fn default() -> Metadata

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for Metadata

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for Metadata

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.