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Package {dasklyr}

Title: R Interface to 'Dask'
Version: 0.1.1
Description: Run 'dplyr' verbs on 'Dask' data frames from R. Connect to a local 'Dask' client or a remote scheduler, copy R data frames onto the cluster, read and write Parquet and CSV, and collect results as 'tibble' objects. Computation stays in Python workers through 'reticulate'; R only builds the graph. A Python installation with the 'dask' package is required.
License: MIT + file LICENSE
Encoding: UTF-8
Language: en-US
Depends: R (≥ 4.1)
Imports: dplyr, rlang, tibble, tidyselect, reticulate (≥ 1.38)
Suggests: testthat (≥ 3.0.0)
Config/testthat/edition: 3
SystemRequirements: Python with the dask (dataframe, distributed), pandas, and pyarrow packages
URL: https://github.com/hebian1994/dasklyr
BugReports: https://github.com/hebian1994/dasklyr/issues
Config/roxygen2/version: 8.1.0
NeedsCompilation: no
Packaged: 2026-10-03 12:00:22 UTC; a
Author: Louis Li [aut, cre, cph]
Maintainer: Louis Li <908163862@qq.com>
Repository: CRAN
Date/Publication: 2026-10-15 16:10:14 UTC

R Interface to Dask

Description

Connect to a Dask cluster from R and run dplyr verbs on Dask DataFrames. Computation stays in Python workers; R builds the graph and collects results.

Details

Point reticulate at a Python that has Dask with environment variables, not hardcoded paths: DASKLYR_PYTHON or RETICULATE_PYTHON. Cluster address: DASK_SCHEDULER (scheduler ⁠tcp://⁠ host and port).

Author(s)

Maintainer: Louis Li 908163862@qq.com [copyright holder]

Authors:

See Also

dask_connect(), copy_to(), dask_read_parquet(), ddf_schema()

Copy an R data frame to Dask

Description

dplyr dplyr::copy_to() method for dask_connection. Counterpart to sparklyr's copy_to.spark_connection. There is no dask_copy_to(); use the dplyr generic, same as sparklyr.

Usage

## S3 method for class 'dask_connection'
copy_to(
  dest,
  df,
  name = deparse(substitute(df)),
  overwrite = FALSE,
  memory = FALSE,
  repartition = 1L,
  ...
)

Arguments

dest

A dask_connection.

df

A data.frame.

name

Table name in the registry.

overwrite

If TRUE, replace an existing name.

memory

If TRUE, persist() the frame after upload.

repartition

Number of Dask partitions. Same argument name as sparklyr (not npartitions).

...

Unused.

Details

Named tables live in a client-side registry (sc$tables), not a Hive catalog. Retrieve them with dplyr::tbl().

Value

A tbl_dask.

Examples

## Not run: 
sc <- dask_connect()
iris_tbl <- copy_to(sc, iris, "iris", overwrite = TRUE)

## End(Not run)

Is Dask available to this R session?

Description

Checks that reticulate can start Python and import dask.dataframe. Honors DASKLYR_PYTHON if set.

Usage

dask_available()

Value

TRUE or FALSE.

Examples

## Not run: 
dask_available()

## End(Not run)

Runtime configuration for dasklyr

Description

Counterpart to sparklyr's spark_config(). Values are stored on the connection object returned by dask_connect().

Usage

dask_config(...)

Arguments

...

Named options. Known keys:

  • timeout: seconds to wait when connecting to a remote scheduler.

  • processes: local Client processes flag (default FALSE).

Value

A named list.

Examples

dask_config(timeout = 30)

Connect to Dask

Description

Counterpart to sparklyr's spark_connect(master = ...). With no arguments, starts a local client. DASK_SCHEDULER is not read here; pass master (or dask_connect(Sys.getenv("DASK_SCHEDULER"))) for a cluster.

Usage

dask_connect(
  master = "local",
  app_name = "dasklyr",
  config = dask_config(),
  timeout = NULL,
  processes = NULL,
  scheduler = NULL,
  ...
)

Arguments

master

"local" starts a local client. A scheduler address such as "tcp://hostname:8786" connects to a cluster.

app_name

Application name used when reusing connections.

config

A list from dask_config().

timeout

Seconds to wait when connecting to a remote scheduler.

processes

Passed to dask.distributed.Client for local masters. Default FALSE avoids Windows process-spawn issues.

scheduler

Alias for master.

...

Unused; present for sparklyr-like call compatibility.

Details

The same master + app_name pair reuses an open connection.

Value

A dask_connection.

Examples

## Not run: 
sc <- dask_connect(master = "local")
sc <- dask_connect(master = Sys.getenv("DASK_SCHEDULER"))

## End(Not run)

Find an open Dask connection

Description

Counterpart to sparklyr's spark_connection_find().

Usage

dask_connection_find(master = NULL, app_name = NULL)

Arguments

master

Scheduler address, or "local". NULL matches any.

app_name

Application name. NULL matches any.

Value

A list of matching dask_connection objects (possibly empty).

Examples

dask_connection_find()

Is a Dask connection still usable?

Description

Is a Dask connection still usable?

Usage

dask_connection_is_open(sc)

Arguments

sc

A dask_connection.

Value

TRUE or FALSE.

Examples

dask_connection_is_open(NULL)

Underlying Dask DataFrame

Description

Counterpart to sparklyr's spark_dataframe(). Returns the Python object so you can call APIs that dasklyr has not wrapped.

Usage

dask_dataframe(x)

Arguments

x

A tbl_dask.

Value

A reticulate Python Dask DataFrame.

Examples

## Not run: 
sc <- dask_connect()
st <- copy_to(sc, mtcars, overwrite = TRUE)
dask_dataframe(st)

## End(Not run)

Disconnect from Dask

Description

Counterpart to sparklyr's spark_disconnect().

Usage

dask_disconnect(sc, ...)

Arguments

sc

A dask_connection.

...

Unused.

Value

sc, invisibly.

Examples

## Not run: 
sc <- dask_connect()
dask_disconnect(sc)

## End(Not run)

Disconnect every open Dask connection

Description

Counterpart to sparklyr's spark_disconnect_all().

Usage

dask_disconnect_all(...)

Arguments

...

Passed to dask_disconnect().

Value

The number of connections closed.

Examples

dask_disconnect_all()

Invoke a Python method

Description

Counterpart to sparklyr's invoke(): call a method on a Dask DataFrame or on the distributed Client. If the result looks like a Dask DataFrame it is wrapped as a tbl_dask.

Usage

dask_invoke(x, method, ...)

## S3 method for class 'tbl_dask'
dask_invoke(x, method, ...)

## S3 method for class 'dask_connection'
dask_invoke(x, method, ...)

Arguments

x

A tbl_dask or dask_connection.

method

Python method name.

...

Arguments forwarded to the Python method.

Value

A tbl_dask if the Python result looks like a Dask DataFrame; otherwise the value returned by reticulate.

Examples

## Not run: 
sc <- dask_connect()
st <- copy_to(sc, mtcars, overwrite = TRUE)
dask_invoke(st, "npartitions")

## End(Not run)

Read CSV or Parquet into a Dask table

Description

Counterpart to sparklyr's spark_read_csv() / spark_read_parquet(). Signature is ⁠(sc, name, path)⁠: name may be omitted and is then derived from the path.

Usage

dask_read_parquet(
  sc,
  name = NULL,
  path = name,
  memory = FALSE,
  overwrite = TRUE,
  ...
)

dask_read_csv(
  sc,
  name = NULL,
  path = name,
  memory = FALSE,
  overwrite = TRUE,
  ...
)

Arguments

sc

A dask_connection.

name

Name to register on sc. If NULL, derived from path.

path

File or glob. Defaults to name when you pass a single path-like argument as sparklyr does.

memory

If TRUE, persist() after read.

overwrite

If TRUE, replace an existing registered name.

...

Extra arguments forwarded to dask.dataframe.read_csv or read_parquet.

Details

path must be visible to workers. A Windows tempfile() is fine for master = "local"; it is not usable from a Docker cluster unless the path is a shared volume or object store.

Value

A tbl_dask.

Examples

## Not run: 
sc <- dask_connect()
pq <- dask_read_parquet(sc, "sales", "/data/sales.parquet")

## End(Not run)

Dask dashboard URL

Description

Counterpart to sparklyr's spark_web().

Usage

dask_web(sc, browse = interactive())

Arguments

sc

A dask_connection.

browse

If TRUE, open the URL in a browser.

Value

The dashboard URL, invisibly.

Examples

## Not run: 
sc <- dask_connect()
dask_web(sc, browse = FALSE)

## End(Not run)

Write a Dask table to Parquet or CSV

Description

Counterpart to sparklyr's spark_write_parquet() / spark_write_csv(). The destination must be writable from workers.

Usage

dask_write_parquet(x, path, mode = NULL, overwrite = FALSE, ...)

dask_write_csv(x, path, mode = NULL, overwrite = FALSE, ...)

Arguments

x

A tbl_dask.

path

Destination path.

mode

"overwrite" is accepted as an alias for overwrite = TRUE.

overwrite

If TRUE, replace existing Parquet files.

...

Extra arguments forwarded to to_parquet / to_csv.

Value

x, invisibly.

Examples

## Not run: 
sc <- dask_connect()
st <- copy_to(sc, mtcars, overwrite = TRUE)
tmp <- tempfile()
dask_write_parquet(st, tmp, overwrite = TRUE)
dask_write_csv(st, tempfile())

## End(Not run)

Table utilities for Dask DataFrames

Description

Counterpart to sparklyr's ⁠sdf_*⁠ helpers. Names use ⁠ddf_*⁠ so they are not mistaken for Spark.

Usage

ddf_schema(x)

ddf_columns(x)

ddf_npartitions(x)

ddf_ncol(x)

ddf_nrow(x)

ddf_dim(x)

ddf_repartition(x, npartitions = NULL, partitions = npartitions)

ddf_persist(x)

Arguments

x

A tbl_dask.

npartitions, partitions

Number of partitions. partitions is an alias for npartitions.

Details

ddf_nrow() computes (len(ddf)). dim() on a tbl_dask reports NA rows on purpose; use this when you need the real count.

Value

ddf_columns() a character vector; ddf_npartitions() / ddf_ncol() / ddf_nrow() integers; ddf_dim() c(nrow, ncol); ddf_schema() a tibble of name and type; ddf_repartition() / ddf_persist() the same tbl_dask with an updated Python frame.

Examples

## Not run: 
sc <- dask_connect()
st <- copy_to(sc, mtcars, overwrite = TRUE, repartition = 2L)
ddf_schema(st)
ddf_npartitions(st)
ddf_nrow(st)
ddf_repartition(st, npartitions = 4L)

## End(Not run)

Objects exported from other packages

Description

These objects are imported from other packages. Follow the links below to see their documentation.

dplyr

copy_to(), src_tbls(), tbl()

Retrieve a registered Dask table

Description

dplyr dplyr::tbl() method for dask_connection.

Usage

## S3 method for class 'dask_connection'
tbl(src, from, ...)

Arguments

src

A dask_connection.

from

Table name previously passed to copy_to() or a read helper.

...

Unused.

Value

A tbl_dask.

Examples

## Not run: 
sc <- dask_connect()
copy_to(sc, iris, "iris", overwrite = TRUE)
tbl(sc, "iris")

## End(Not run)

Distributed Dask tables

Description

A tbl_dask is a lazy Dask DataFrame plus optional grouping columns. print() and head() preview the first partition (Dask's DataFrame.head). Use dplyr::slice_head() when you need a global first-n (that path collects, then wraps the result).

Usage

## S3 method for class 'tbl_dask'
print(x, n = 6L, ...)

## S3 method for class 'tbl_dask'
head(x, n = 6L, ...)

## S3 method for class 'tbl_dask'
dim(x)

## S3 method for class 'tbl_dask'
colnames(x, ...)

## S3 method for class 'tbl_dask'
names(x)

## S3 method for class 'tbl_dask'
collect(x, ...)

Arguments

x

A tbl_dask.

n

Number of rows to preview.

...

Unused.

Details

dplyr::collect() computes the full frame, resets the pandas index, and returns a tibble.

Value

print() and head() return a tibble preview; collect() a tibble of the full compute; dim() is c(NA, ncol); names() / colnames() a character vector of column names.

Examples

## Not run: 
sc <- dask_connect()
st <- copy_to(sc, mtcars, overwrite = TRUE)
names(st)
head(st, 3)
dplyr::collect(st)

## End(Not run)

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