use crate::{
PolarsPlugin,
dataframe::{utils::extract_strings, values::NuLazyFrame},
values::{
CustomValueSupport, NuExpression, PolarsPluginObject, PolarsPluginType, cant_convert_err,
},
};
use crate::values::{Column, NuDataFrame};
use nu_plugin::{EngineInterface, EvaluatedCall, PluginCommand};
use nu_protocol::shell_error::generic::GenericError;
use nu_protocol::{
Category, Example, LabeledError, PipelineData, ShellError, Signature, Span, SyntaxShape, Value,
};
use polars::prelude::{IntoSeries, UniqueKeepStrategy, cols};
#[derive(Clone)]
pub struct Unique;
impl PluginCommand for Unique {
type Plugin = PolarsPlugin;
fn name(&self) -> &str {
"polars unique"
}
fn description(&self) -> &str {
"Returns unique values from a dataframe."
}
fn signature(&self) -> Signature {
Signature::build(self.name())
.named(
"subset",
SyntaxShape::Any,
"Subset of column(s) to use to maintain rows (lazy df).",
Some('s'),
)
.switch(
"last",
"Keeps last unique value. Default keeps first value (lazy df).",
Some('l'),
)
.switch(
"maintain-order",
"Keep the same order as the original DataFrame (lazy df).",
Some('k'),
)
.input_output_types(vec![
(
PolarsPluginType::NuDataFrame.into(),
PolarsPluginType::NuDataFrame.into(),
),
(
PolarsPluginType::NuLazyFrame.into(),
PolarsPluginType::NuLazyFrame.into(),
),
(
PolarsPluginType::NuExpression.into(),
PolarsPluginType::NuExpression.into(),
),
])
.category(Category::Custom("dataframe or lazyframe".into()))
}
fn examples(&self) -> Vec<Example<'_>> {
vec![
Example {
description: "Returns unique values from a series",
example: "[2 2 2 2 2] | polars into-df | polars unique",
result: Some(
NuDataFrame::try_from_columns(
vec![Column::new("0".to_string(), vec![Value::test_int(2)])],
None,
Span::test_data(),
)
.expect("simple df for test should not fail")
.into_value(Span::test_data()),
),
},
Example {
description: "Returns unique values in a subset of lazyframe columns",
example: "[[a b c]; [1 2 1] [2 2 2] [3 2 1]] | polars into-lazy | polars unique --subset [b c] | polars collect",
result: Some(
NuDataFrame::try_from_columns(
vec![
Column::new(
"a".to_string(),
vec![Value::test_int(1), Value::test_int(2)],
),
Column::new(
"b".to_string(),
vec![Value::test_int(2), Value::test_int(2)],
),
Column::new(
"c".to_string(),
vec![Value::test_int(1), Value::test_int(2)],
),
],
None,
Span::test_data(),
)
.expect("simple df for test should not fail")
.into_value(Span::test_data()),
),
},
Example {
description: "Returns unique values in a subset of lazyframe columns",
example: r#"[[a b c]; [1 2 1] [2 2 2] [3 2 1]]
| polars into-lazy
| polars unique --subset [b c] --last
| polars collect"#,
result: Some(
NuDataFrame::try_from_columns(
vec![
Column::new(
"a".to_string(),
vec![Value::test_int(2), Value::test_int(3)],
),
Column::new(
"b".to_string(),
vec![Value::test_int(2), Value::test_int(2)],
),
Column::new(
"c".to_string(),
vec![Value::test_int(2), Value::test_int(1)],
),
],
None,
Span::test_data(),
)
.expect("simple df for test should not fail")
.into_value(Span::test_data()),
),
},
Example {
description: "Returns unique values in a subset of lazyframe columns",
example: r#"[[a]; [2] [1] [2]]
| polars into-lazy
| polars select (polars col a | polars unique)
| polars collect"#,
result: Some(
NuDataFrame::try_from_columns(
vec![Column::new(
"a".to_string(),
vec![Value::test_int(1), Value::test_int(2)],
)],
None,
Span::test_data(),
)
.expect("simple df for test should not fail")
.into_value(Span::test_data()),
),
},
Example {
description: "Returns unique values in a subset of lazyframe columns",
example: r#"[[a]; [2] [1] [2]]
| polars into-lazy
| polars select (polars col a | polars unique --maintain-order)
| polars collect"#,
result: Some(
NuDataFrame::try_from_columns(
vec![Column::new(
"a".to_string(),
vec![Value::test_int(2), Value::test_int(1)],
)],
None,
Span::test_data(),
)
.expect("simple df for test should not fail")
.into_value(Span::test_data()),
),
},
]
}
fn run(
&self,
plugin: &Self::Plugin,
engine: &EngineInterface,
call: &EvaluatedCall,
mut input: PipelineData,
) -> Result<PipelineData, LabeledError> {
let metadata = input.take_metadata();
let value = input.into_value(call.head)?;
match PolarsPluginObject::try_from_value(plugin, &value)? {
PolarsPluginObject::NuDataFrame(df) => command_eager(plugin, engine, call, df),
PolarsPluginObject::NuLazyFrame(lazy) => command_lazy(plugin, engine, call, lazy),
PolarsPluginObject::NuExpression(expr) => {
let maintain = call.has_flag("maintain-order")?;
let res: NuExpression = if maintain {
expr.into_polars().unique_stable().into()
} else {
expr.into_polars().unique().into()
};
res.to_pipeline_data(plugin, engine, call.head)
}
_ => Err(cant_convert_err(
&value,
&[
PolarsPluginType::NuDataFrame,
PolarsPluginType::NuLazyGroupBy,
PolarsPluginType::NuExpression,
],
)),
}
.map_err(LabeledError::from)
.map(|pd| pd.set_metadata(metadata))
}
}
fn command_eager(
plugin: &PolarsPlugin,
engine: &EngineInterface,
call: &EvaluatedCall,
df: NuDataFrame,
) -> Result<PipelineData, ShellError> {
let series = df.as_series(call.head)?;
let res = series.unique().map_err(|e| {
ShellError::Generic(
GenericError::new("Error calculating unique values", e.to_string(), call.head)
.with_help("The str-slice command can only be used with string columns"),
)
})?;
let df = NuDataFrame::try_from_series_vec(vec![res.into_series()], call.head)?;
df.to_pipeline_data(plugin, engine, call.head)
}
fn command_lazy(
plugin: &PolarsPlugin,
engine: &EngineInterface,
call: &EvaluatedCall,
lazy: NuLazyFrame,
) -> Result<PipelineData, ShellError> {
let last = call.has_flag("last")?;
let maintain = call.has_flag("maintain-order")?;
let subset: Option<Value> = call.get_flag("subset")?;
let subset = match subset {
Some(value) => Some(cols(extract_strings(value)?)),
None => None,
};
let strategy = if last {
UniqueKeepStrategy::Last
} else {
UniqueKeepStrategy::First
};
let lazy = lazy.to_polars();
let lazy: NuLazyFrame = if maintain {
lazy.unique(subset, strategy).into()
} else {
lazy.unique_stable(subset, strategy).into()
};
lazy.to_pipeline_data(plugin, engine, call.head)
}
#[cfg(test)]
mod test {
use super::*;
use crate::test::test_polars_plugin_command;
#[test]
fn test_examples() -> Result<(), ShellError> {
test_polars_plugin_command(&Unique)
}
}