use crate::prelude::*; use nu_engine::WholeStreamCommand; use nu_errors::ShellError; use nu_protocol::{ dataframe::{Column, NuDataFrame}, Signature, UntaggedValue, }; use polars::prelude::{IntoSeries, NewChunkedArray, UInt32Chunked}; pub struct DataFrame; impl WholeStreamCommand for DataFrame { fn name(&self) -> &str { "dataframe arg-max" } fn usage(&self) -> &str { "[Series] Return index for max value in series" } fn signature(&self) -> Signature { Signature::build("dataframe arg-max") } fn run(&self, args: CommandArgs) -> Result { command(args) } fn examples(&self) -> Vec { vec![Example { description: "Returns index for max value", example: "[1 3 2] | dataframe to-df | dataframe arg-max", result: Some(vec![NuDataFrame::try_from_columns( vec![Column::new( "arg_max".to_string(), vec![UntaggedValue::int(1).into()], )], &Span::default(), ) .expect("simple df for test should not fail") .into_value(Tag::default())]), }] } } fn command(mut args: CommandArgs) -> Result { let tag = args.call_info.name_tag.clone(); let (df, df_tag) = NuDataFrame::try_from_stream(&mut args.input, &tag.span)?; let series = df.as_series(&df_tag.span)?; let res = series.arg_max(); let chunked = match res { Some(index) => UInt32Chunked::new_from_slice("arg_max", &[index as u32]), None => UInt32Chunked::new_from_slice("arg_max", &[]), }; let res = chunked.into_series(); let df = NuDataFrame::try_from_series(vec![res], &tag.span)?; Ok(OutputStream::one(df.into_value(df_tag))) } #[cfg(test)] mod tests { use super::DataFrame; use super::ShellError; #[test] fn examples_work_as_expected() -> Result<(), ShellError> { use crate::examples::test_dataframe as test_examples; test_examples(DataFrame {}) } }