Expression Syntax Reference¶

Several hipo-utils tools support filtering events using expressions. This page documents the complete expression syntax.

Basic Format¶

Bank::Name.column operator value

Components:

Bank::Name - The bank name (e.g., REC::Particle, MC::True)
column - The column name within the bank (e.g., pid, px, status)
operator - Comparison operator
value - Value to compare against

Comparison Operators¶

Operator	Meaning	Example
`==`	Equal to	`REC::Particle.pid == 11`
`!=`	Not equal to	`REC::Particle.charge != 0`
`<`	Less than	`REC::Particle.p < 1.0`
`<=`	Less than or equal	`REC::Track.ndf <= 5`
`>`	Greater than	`REC::Particle.beta > 0.9`
`>=`	Greater than or equal	`REC::Track.chi2 >= 0`

Set Membership (IN)¶

Test if a value is in a list:

Bank::Name.column IN (value1, value2, ...)

Examples:

# Match electrons or muons
REC::Particle.pid IN (11, 13)

# Match specific status codes
REC::Particle.status IN (2000, 4000)

Note

The IN keyword is case-insensitive (IN, in, In all work).

Range Testing (BETWEEN)¶

Test if a value is within a range (inclusive):

Bank::Name.column BETWEEN min AND max

Examples:

# Momentum between 0.5 and 2.0 GeV
REC::Particle.p BETWEEN 0.5 AND 2.0

# Beta between 0.9 and 1.1
REC::Particle.beta BETWEEN 0.9 AND 1.1

Note

BETWEEN and AND are case-insensitive. The range is inclusive on both ends.

Multiple Expressions¶

AND Logic (Default)¶

When multiple -e options are provided, ALL must match (AND logic):

hipo-filter -e "REC::Particle.pid == 11" \
            -e "REC::Particle.p > 1.0" \
            -o output.hipo input.hipo

OR Logic¶

Use --or to match ANY expression:

hipo-filter -e "REC::Particle.pid == 11" \
            -e "REC::Particle.pid == -11" \
            --or \
            -o output.hipo input.hipo

Matching Behavior¶

Any-Row Matching

An expression matches an event if ANY row in the specified bank satisfies the condition. For example:

REC::Particle.pid == 11

Matches an event if at least one particle has pid=11, even if other particles have different pid values.

Supported Data Types¶

Expressions work with all numeric column types:

HIPO Type	Description
`Byte`	8-bit signed integer
`Short`	16-bit signed integer
`Int`	32-bit signed integer
`Long`	64-bit signed integer
`Float`	32-bit floating point
`Double`	64-bit floating point

Tools Using Expressions¶

Tool	Options
hipo-filter	`-e, --expr`
hipo-search	`-e, --expr`

Examples¶

Common Physics Filters¶

# Electrons
REC::Particle.pid == 11

# Positrons
REC::Particle.pid == -11

# Charged particles
REC::Particle.charge != 0

# Neutral particles
REC::Particle.charge == 0

# Photons
REC::Particle.pid == 22

# Protons
REC::Particle.pid == 2212

# Neutrons
REC::Particle.pid == 2112

# Pions (charged)
REC::Particle.pid IN (211, -211)

# Pions (all)
REC::Particle.pid IN (211, -211, 111)

# Leptons
REC::Particle.pid IN (11, -11, 13, -13)

# High momentum particles
REC::Particle.p > 2.0

# Forward detector particles
REC::Particle.status BETWEEN 2000 AND 2999

# Central detector particles
REC::Particle.status BETWEEN 4000 AND 4999

Combined Filters¶

# High-momentum electrons
hipo-filter -e "REC::Particle.pid == 11" \
            -e "REC::Particle.p > 1.0" \
            -o high_p_electrons.hipo data.hipo

# Events with good track quality
hipo-filter -e "REC::Track.ndf >= 15" \
            -e "REC::Track.chi2 < 10" \
            -o good_tracks.hipo data.hipo