nushell/crates/nu-command/src/dataframe/eager/get.rs

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use nu_engine::CallExt;
use nu_protocol::{
ast::Call,
engine::{Command, EngineState, Stack},
Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
};
use crate::dataframe::values::utils::convert_columns_string;
use super::super::values::{Column, NuDataFrame};
#[derive(Clone)]
pub struct GetDF;
impl Command for GetDF {
fn name(&self) -> &str {
"get"
}
fn usage(&self) -> &str {
"Creates dataframe with the selected columns"
}
fn signature(&self) -> Signature {
Signature::build(self.name())
.rest("rest", SyntaxShape::Any, "column names to sort dataframe")
.category(Category::Custom("dataframe".into()))
}
fn examples(&self) -> Vec<Example> {
vec![Example {
description: "Returns the selected column",
example: "[[a b]; [1 2] [3 4]] | to-df | get a",
result: Some(
NuDataFrame::try_from_columns(vec![Column::new(
"a".to_string(),
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vec![Value::test_int(1), Value::test_int(3)],
)])
.expect("simple df for test should not fail")
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.into_value(Span::test_data()),
),
}]
}
fn input_type(&self) -> Type {
Type::Custom("dataframe".into())
}
fn output_type(&self) -> Type {
Type::Custom("dataframe".into())
}
fn run(
&self,
engine_state: &EngineState,
stack: &mut Stack,
call: &Call,
input: PipelineData,
) -> Result<PipelineData, ShellError> {
command(engine_state, stack, call, input)
}
}
fn command(
engine_state: &EngineState,
stack: &mut Stack,
call: &Call,
input: PipelineData,
) -> Result<PipelineData, ShellError> {
let columns: Vec<Value> = call.rest(engine_state, stack, 0)?;
let (col_string, col_span) = convert_columns_string(columns, call.head)?;
let df = NuDataFrame::try_from_pipeline(input, call.head)?;
df.as_ref()
.select(&col_string)
.map_err(|e| {
ShellError::GenericError(
"Error selecting columns".into(),
e.to_string(),
Some(col_span),
None,
Vec::new(),
)
})
.map(|df| PipelineData::Value(NuDataFrame::dataframe_into_value(df, call.head), None))
}
#[cfg(test)]
mod test {
use super::super::super::test_dataframe::test_dataframe;
use super::*;
#[test]
fn test_examples() {
test_dataframe(vec![Box::new(GetDF {})])
}
}