Internals
The functions, methods and types listed on this page are internal to DataFrames and are not considered to be part of the public API. |
#
DataFrames.compacttype
— Function
compacttype(T::Type, maxwidth::Int=8, initial::Bool=true)
Return compact string representation of type T
.
For displaying data frame we do not want string representation of type to be longer than maxwidth
. This function implements rules how type names are cropped if they are longer than maxwidth
.
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DataFrames.gennames
— Function
gennames(n::Integer)
Generate standardized names for columns of a DataFrame. The first name will be :x1
, the second :x2
, etc.
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DataFrames.getmaxwidths
— Function
DataFrames.getmaxwidths(df::AbstractDataFrame,
io::IO,
rowindices1::AbstractVector{Int},
rowindices2::AbstractVector{Int},
rowlabel::Symbol,
rowid::Union{Integer, Nothing},
show_eltype::Bool,
buffer::IOBuffer)
Calculate, for each column of an AbstractDataFrame, the maximum string width used to render the name of that column, its type, and the longest entry in that column — among the rows of the data frame will be rendered to IO. The widths for all columns are returned as a vector.
Return a Vector{Int}
giving the maximum string widths required to render each column, including that column’s name and type.
The last entry of the result vector is the string width of the implicit row ID column contained in every AbstractDataFrame .
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Arguments
-
df::AbstractDataFrame
: The data frame whose columns will be printed. -
io::IO
: TheIO
to whichdf
is to be printed -
`rowindices1::AbstractVector{Int}: A set of indices of the first chunk of the AbstractDataFrame that would be rendered to IO.
-
`rowindices2::AbstractVector{Int}: A set of indices of the second chunk of the AbstractDataFrame that would be rendered to IO. Can be empty if the AbstractDataFrame would be printed without any ellipses.
-
rowlabel::AbstractString
: The label that will be used when rendered the numeric ID’s of each row. Typically, this will be set to "Row". -
rowid
: Used to handle showingDataFrameRow
. -
show_eltype
: Whether to print the column type under the column name in the heading. -
buffer
: buffer passed around to avoid reallocations inourstrwidth
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DataFrames.ourshow
— Function
DataFrames.ourshow(io::IO, x::Any, truncstring::Int)
Render a value to an IO
object compactly using print. truncstring
indicates the approximate number of text characters width to truncate the output (if it is a non-positive value then no truncation is applied).
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DataFrames.ourstrwidth
— Function
DataFrames.ourstrwidth(io::IO, x::Any, buffer::IOBuffer, truncstring::Int)
Determine the number of characters that would be used to print a value.
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DataFrames.@spawn_for_chunks
— Macro
@spawn_for_chunks basesize for i in range ... end
Parallelize a for
loop by spawning separate tasks iterating each over a chunk of at least basesize
elements in range
.
A number of tasks higher than Threads.nthreads()
may be spawned, since that can allow for a more efficient load balancing in case some threads are busy (nested parallelism).
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DataFrames.@spawn_or_run_task
— Macro
@spawn_or_run_task threads expr
Equivalent to Threads.@spawn
if threads === true
, otherwise run expr
and return a Task
that returns its value.
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DataFrames.@spawn_or_run
— Macro
@spawn_or_run threads expr
Equivalent to Threads.@spawn
if threads === true
, otherwise run expr
.
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DataFrames.default_table_transformation
— Function
default_table_transformation(df_sel::AbstractDataFrame, fun)
This is a default implementation called when AsTable(...) => fun
is requested. The df_sel
argument is a data frame storing columns selected by AsTable(...)
selector.
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DataFrames.isreadonly
— Function
isreadonly(fun)
Trait returning a Bool
indicator if function fun
is only reading the passed argument. Such a function guarantees not to modify nor return in any form the passed argument. By default false
is returned.
This function might become a part of the public API of DataFrames.jl in the future, currently it should be considered experimental. Adding a method to isreadonly
for a specific function fun
will improve performance of AsTable(...) => ByRow(fun∘collect)
operation.