nushell/crates/nu-cli/src/commands/map_max_by.rs

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use crate::commands::WholeStreamCommand;
use crate::data::value;
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use crate::prelude::*;
use crate::utils::data_processing::map_max;
use nu_errors::ShellError;
use nu_protocol::{Primitive, ReturnSuccess, Signature, SyntaxShape, UntaggedValue, Value};
use nu_source::Tagged;
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use num_traits::cast::ToPrimitive;
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pub struct MapMaxBy;
#[derive(Deserialize)]
pub struct MapMaxByArgs {
column_name: Option<Tagged<String>>,
}
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#[async_trait]
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impl WholeStreamCommand for MapMaxBy {
fn name(&self) -> &str {
"map-max-by"
}
fn signature(&self) -> Signature {
Signature::build("map-max-by").named(
"column_name",
SyntaxShape::String,
"the name of the column to map-max the table's rows",
Some('c'),
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)
}
fn usage(&self) -> &str {
"Creates a new table with the data from the tables rows maxed by the column given."
}
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async fn run(
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&self,
args: CommandArgs,
registry: &CommandRegistry,
) -> Result<OutputStream, ShellError> {
map_max_by(args, registry).await
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}
}
pub async fn map_max_by(
args: CommandArgs,
registry: &CommandRegistry,
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) -> Result<OutputStream, ShellError> {
let registry = registry.clone();
let name = args.call_info.name_tag.clone();
let (MapMaxByArgs { column_name }, mut input) = args.process(&registry).await?;
let values: Vec<Value> = input.collect().await;
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if values.is_empty() {
Err(ShellError::labeled_error(
"Expected table from pipeline",
"requires a table input",
name,
))
} else {
let map_by_column = if let Some(column_to_map) = column_name {
Some(column_to_map.item().clone())
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} else {
None
};
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match map_max(&values[0], map_by_column, name) {
Ok(table_maxed) => Ok(OutputStream::one(ReturnSuccess::value(table_maxed))),
Err(err) => Err(err),
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}
}
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}
#[cfg(test)]
mod tests {
use super::MapMaxBy;
#[test]
fn examples_work_as_expected() {
use crate::examples::test as test_examples;
test_examples(MapMaxBy {})
}
}