78 lines
2.2 KiB
Rust
78 lines
2.2 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, SyntaxShape, Value,
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};
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use super::super::values::{utils::convert_columns_string, NuDataFrame, NuGroupBy};
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#[derive(Clone)]
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pub struct CreateGroupBy;
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impl Command for CreateGroupBy {
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fn name(&self) -> &str {
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"dfr group-by"
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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(self.name())
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.rest("rest", SyntaxShape::Any, "groupby columns")
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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![Example {
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description: "Grouping by column a",
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example: "[[a b]; [one 1] [one 2]] | dfr to-df | dfr group-by a",
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result: None,
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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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// Extracting the names of the columns to perform the groupby
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let columns: Vec<Value> = call.rest(engine_state, stack, 0)?;
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let (col_string, col_span) = convert_columns_string(columns, call.head)?;
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let df = NuDataFrame::try_from_pipeline(input, call.head)?;
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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 = df.as_ref().groupby(&col_string).map_err(|e| {
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ShellError::GenericError(
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"Error creating groupby".into(),
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e.to_string(),
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Some(col_span),
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None,
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Vec::new(),
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)
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})?;
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let groups = groupby.get_groups();
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let groupby = NuGroupBy::new(df.as_ref().clone(), col_string, groups);
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Ok(PipelineData::Value(groupby.into_value(call.head), None))
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}
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