5537dce3cc
* Sample command * Join command with checks * More dataframes commands * Groupby and aggregate commands * Missing feature dataframe flag * Renamed file * New commands for dataframes * error parser and df reference * filter command for dataframes * removed name from nu_dataframe * commands to save to parquet and csv
91 lines
2.9 KiB
Rust
91 lines
2.9 KiB
Rust
use crate::{commands::dataframe::utils::parse_polars_error, prelude::*};
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use nu_engine::WholeStreamCommand;
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use nu_errors::ShellError;
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use nu_protocol::{
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dataframe::{NuDataFrame, NuGroupBy, PolarsData},
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Signature, SyntaxShape, UntaggedValue, Value,
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};
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use super::utils::convert_columns;
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pub struct DataFrame;
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impl WholeStreamCommand for DataFrame {
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fn name(&self) -> &str {
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"pls groupby"
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}
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fn usage(&self) -> &str {
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"Creates a groupby object that can be used for other aggregations"
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}
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fn signature(&self) -> Signature {
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Signature::build("pls groupby").required(
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"by columns",
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SyntaxShape::Table,
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"groupby columns",
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)
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}
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fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
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command(args)
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}
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fn examples(&self) -> Vec<Example> {
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vec![Example {
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description: "Grouping by column a",
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example: "[[a b]; [one 1] [one 2]] | pls convert | pls groupby [a]",
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result: None,
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}]
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}
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}
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fn command(args: CommandArgs) -> Result<OutputStream, ShellError> {
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let tag = args.call_info.name_tag.clone();
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let mut args = args.evaluate_once()?;
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// Extracting the names of the columns to perform the groupby
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let by_columns: Vec<Value> = args.req(0)?;
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let (columns_string, col_span) = convert_columns(&by_columns, &tag)?;
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// The operation is only done in one dataframe. Only one input is
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// expected from the InputStream
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match args.input.next() {
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None => Err(ShellError::labeled_error(
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"No input received",
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"missing dataframe input from stream",
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&tag,
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)),
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Some(value) => {
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if let UntaggedValue::DataFrame(PolarsData::EagerDataFrame(nu_df)) = value.value {
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// This is the expensive part of the groupby; to create the
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// groups that will be used for grouping the data in the
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// dataframe. Once it has been done these values can be stored
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// in a NuGroupBy
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let groupby = nu_df
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.as_ref()
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.groupby(&columns_string)
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.map_err(|e| parse_polars_error::<&str>(&e, &col_span, None))?;
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let groups = groupby.get_groups().to_vec();
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let groupby = Value {
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tag: value.tag,
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value: UntaggedValue::DataFrame(PolarsData::GroupBy(NuGroupBy::new(
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NuDataFrame::new(nu_df.as_ref().clone()),
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columns_string,
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groups,
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))),
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};
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Ok(OutputStream::one(groupby))
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} else {
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Err(ShellError::labeled_error(
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"No dataframe in stream",
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"no dataframe found in input stream",
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&tag,
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))
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}
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}
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}
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}
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