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Episode 0: Hello World

Metaflow says Hi!

This flow is a simple linear workflow that verifies your installation by printing out Metaflow says: Hi!' to the terminal.

Showcasing:

To play this episode:

If you haven't yet pulled the tutorials to your current working directory, you can follow the instructions here.

  1. cd tutorials/00-helloworld
  2. Rscript helloworld.R show
  3. Rscript helloworld.R run

The flow script below prints 'Hi' in Metaflow. Run this flow to validate that Metaflow is installed correctly.

helloworld.R
library(metaflow)

# This is the 'start' step. All flows must have a step named
# 'start' that is the first step in the flow.
start <- function(self){
print("HelloFlow is starting.")
}

# A step for metaflow to introduce itself.
hello <- function(self){
print("Metaflow says: Hi!")
}

# This is the 'end' step. All flows must have an 'end' step,
# which is the last step in the flow.
end <- function(self){
print("HelloFlow is all done.")
}

metaflow("HelloFlow") %>%
step(step = "start",
r_function = start,
next_step = "hello") %>%
step(step = "hello",
r_function = hello,
next_step = "end") %>%
step(step = "end",
r_function = end) %>%
run()