Supported YAML Tags
YAML allows defining custom so-called tags which can be distinguished during loading and serialization of objects.
paramspace
makes heavy use of this possibility, as it greatly simplifies the definition and usage of configuration files.
paramspace
-related tags
The paramspace.yaml
module implements constructors and representers for the following classes:
!pspace
constructs aParamSpace
!pdim
constructs aParamDim
!coupled-pdim
constructs aCoupledParamDim
This is a very convenient way of defining these objects.
Hint
For the ParamDim
and derived classes, there additionally are the !pdim-default
and !coupled-pdim-default
tags.
These do not create a ParamDim
objects but directly return the default value.
By adding the -default
in the end, they can be quickly deactivated inside the configuration file (as an alternative to commenting them out).
Python builtins and basic operators
paramspace.yaml
adds YAML constructors for a number of frequently used Python built-in functions and operators.
Having these available while specifying configurations can make the definition of configurations files more versatile.
Warning
The YAML tags provided here are only meant to allow basic operations, i.e. summing two parameters to create a third. Don’t overdo it. Configuration files should remain easy to read.
The tags shown below call the equivalent Python builtin or the operators defined in the operator
Python module.
Example:
any: !any [false, 0, true] # == True
all: !all [true, 5, 0] # == False
abs: !abs -1 # +1
int: !int 1.23 # 1
round: !round 9.87 # 10
sum: !sum [1, 2, 3] # 6
prod: !prod [2, 3, 4] # 24
min: !min [1, 2, 3] # 1
max: !max [1, 2, 3] # 3
sorted: !sorted [2, 1, 3] # [1, 2, 3]
isorted: !isorted [2, 1, 3] # [3, 2, 1]
# Operators
add: !add [1, 2] # 1 + 2
sub: !sub [2, 1] # 2 - 1
mul: !mul [3, 4] # 3 * 4
mod: !mod [3, 2] # 3 % 2
pow: !pow [2, 4] # 2 ** 4
truediv: !truediv [3, 2] # 3 / 2
floordiv: !floordiv [3, 2] # 3 // 2
pow_mod: !pow [2, 4, 3] # 2 ** 4 % 3
not: !not [true]
and: !and [true, false]
or: !or [true, false]
xor: !xor [true, true]
lt: !lt [1, 2] # 1 < 2
le: !le [2, 2] # 2 <= 2
eq: !eq [3, 3] # 3 == 3
ne: !ne [3, 1] # 3 != 1
ge: !ge [2, 2] # 2 >= 2
gt: !gt [4, 3] # 4 > 3
negate: !negate [1] # -1
invert: !invert [true] # ~true
contains: !contains [[1,2,3], 4] # 4 in [1,2,3] == False
concat: !concat [[1,2,3], [4,5], [6,7,8]] # […]+[…]+[…]+…
# List generation
# ... using the paramspace.tools.create_indices function
list1: !listgen [0, 10, 2] # [0, 2, 4, 6, 8]
list2: !listgen
from_range: [0, 10, 3]
unique: true
append: [100]
remove: [0]
sort: true
# ... using np.linspace, np.logspace, np.arange
lin: !linspace [-1, 1, 5] # [-1., -.5, 0., .5, 1.]
log: !logspace [1, 4, 4] # [10., 100., 1000., 10000.]
arange: !arange [0, 1, .2] # [0., .2, .4, .6, .8]
# String formatting
format1: !format ["{} is not {}", foo, bar]
format2: !format
fstr: "{some_key:}: {some_value:}"
some_key: fish
some_value: spam
format3: !format
fstr: "results: {stats[mean]:.2f} ± {stats[std]:.2f}"
stats:
mean: 1.632
std: 0.026
# Reading environment variables, optionally with fallback
PATH: !getenv PATH # fails if variable is missing
username: !getenv [USER, "unknown_user"]
home_directory: !getenv [HOME, "/"]
Recursively updating maps
While YAML already provides the <<
operator to update a mapping, this operator does not work recursively.
The !rec-update
YAML tag supplies exactly that functionality using the recursive_update()
function.
some_map: &some_map
foo: bar
spam: fish
some_other_map: &some_other_map
foo:
bar: baz
baz: bar
fish: spam
# Create a new map by recursively updating the first map with
# the second one (uses deep copies to avoid side effects)
merged: !rec-update [<<: *some_map, <<: *some_other_map]
# NOTE: Need to use ^^-- inheritance here, otherwise this will
# result in empty mappings (for some reason)
Warning
Always include via <<: *my_ref
!
If supplying references to mappings (as shown in the example), the references have to be included using <<: *my_ref
!
Otherwise, if using the simple *my_ref
as argument, the YAML parser does not properly resolve the reference to the anchor but only returns an empty mapping.