133 lines
4.1 KiB
Rust
133 lines
4.1 KiB
Rust
use nu_engine::CallExt;
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use nu_protocol::{
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ast::Call,
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engine::{Command, EngineState, Stack},
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Category, Example, PipelineData, ShellError, Signature, Spanned, SyntaxShape, Type,
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};
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use super::super::values::NuDataFrame;
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#[derive(Clone)]
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pub struct SampleDF;
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impl Command for SampleDF {
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fn name(&self) -> &str {
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"sample"
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}
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fn usage(&self) -> &str {
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"Create sample dataframe"
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}
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fn signature(&self) -> Signature {
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Signature::build(self.name())
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.named(
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"n-rows",
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SyntaxShape::Int,
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"number of rows to be taken from dataframe",
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Some('n'),
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)
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.named(
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"fraction",
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SyntaxShape::Number,
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"fraction of dataframe to be taken",
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Some('f'),
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)
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.named(
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"seed",
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SyntaxShape::Number,
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"seed for the selection",
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Some('s'),
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)
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.switch("replace", "sample with replace", Some('e'))
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.switch("shuffle", "shuffle sample", Some('u'))
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.input_type(Type::Custom("dataframe".into()))
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.output_type(Type::Custom("dataframe".into()))
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.category(Category::Custom("dataframe".into()))
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}
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fn examples(&self) -> Vec<Example> {
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vec![
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Example {
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description: "Sample rows from dataframe",
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example: "[[a b]; [1 2] [3 4]] | into df | sample -n 1",
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result: None, // No expected value because sampling is random
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},
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Example {
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description: "Shows sample row using fraction and replace",
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example: "[[a b]; [1 2] [3 4] [5 6]] | into df | sample -f 0.5 -e",
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result: None, // No expected value because sampling is random
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},
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]
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}
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fn run(
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&self,
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engine_state: &EngineState,
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stack: &mut Stack,
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call: &Call,
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input: PipelineData,
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) -> Result<PipelineData, ShellError> {
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command(engine_state, stack, call, input)
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}
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}
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fn command(
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engine_state: &EngineState,
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stack: &mut Stack,
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call: &Call,
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input: PipelineData,
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) -> Result<PipelineData, ShellError> {
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let rows: Option<Spanned<usize>> = call.get_flag(engine_state, stack, "n-rows")?;
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let fraction: Option<Spanned<f64>> = call.get_flag(engine_state, stack, "fraction")?;
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let seed: Option<u64> = call
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.get_flag::<i64>(engine_state, stack, "seed")?
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.map(|val| val as u64);
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let replace: bool = call.has_flag("replace");
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let shuffle: bool = call.has_flag("shuffle");
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let df = NuDataFrame::try_from_pipeline(input, call.head)?;
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match (rows, fraction) {
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(Some(rows), None) => df
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.as_ref()
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.sample_n(rows.item, replace, shuffle, seed)
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.map_err(|e| {
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ShellError::GenericError(
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"Error creating sample".into(),
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e.to_string(),
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Some(rows.span),
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None,
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Vec::new(),
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)
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}),
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(None, Some(frac)) => df
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.as_ref()
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.sample_frac(frac.item, replace, shuffle, seed)
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.map_err(|e| {
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ShellError::GenericError(
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"Error creating sample".into(),
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e.to_string(),
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Some(frac.span),
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None,
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Vec::new(),
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)
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}),
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(Some(_), Some(_)) => Err(ShellError::GenericError(
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"Incompatible flags".into(),
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"Only one selection criterion allowed".into(),
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Some(call.head),
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None,
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Vec::new(),
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)),
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(None, None) => Err(ShellError::GenericError(
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"No selection".into(),
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"No selection criterion was found".into(),
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Some(call.head),
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Some("Perhaps you want to use the flag -n or -f".into()),
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Vec::new(),
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)),
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}
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.map(|df| PipelineData::Value(NuDataFrame::dataframe_into_value(df, call.head), None))
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}
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