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af77bc60e2
# Description Fixes: #12726 and #13185 Previously converting columns that contained null caused polars to force a dtype of object even when using a schema. Now: 1. When using a schema, the type the schema defines for the column will always be used. 2. When a schema is not used, the previous type is used when a value is null. # User-Facing Changes - The type defined by the schema we be respected when passing in a null value `[a]; [null] | polars into-df -s {a: str}` will create a df with an str dtype column with one null value versus a column of type object. - *BREAKING CHANGE* If you define a schema, all columns must be in the schema.
88 lines
2.5 KiB
Rust
88 lines
2.5 KiB
Rust
use crate::dataframe::values::NuExpression;
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use crate::values::{
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cant_convert_err, CustomValueSupport, NuDataFrame, PolarsPluginObject, PolarsPluginType,
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};
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use crate::PolarsPlugin;
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use nu_plugin::{EngineInterface, EvaluatedCall, PluginCommand};
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use nu_protocol::{
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Category, Example, LabeledError, PipelineData, ShellError, Signature, Span, Type,
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};
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use polars::df;
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pub struct ExprCount;
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impl PluginCommand for ExprCount {
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type Plugin = PolarsPlugin;
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fn name(&self) -> &str {
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"polars count"
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}
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fn description(&self) -> &str {
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"Returns the number of non-null values in the column."
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}
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fn signature(&self) -> Signature {
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Signature::build(self.name())
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.input_output_types(vec![(
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Type::Custom("expression".into()),
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Type::Custom("expression".into()),
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)])
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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: "Count the number of non-null values in a column",
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example: r#"[[a]; ["foo"] ["bar"] [null]] | polars into-df
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| polars select (polars col a | polars count)
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| polars collect"#,
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result: Some(
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NuDataFrame::from(
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df!(
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"a" => [2]
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)
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.expect("should not fail"),
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)
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.into_value(Span::unknown()),
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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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plugin: &Self::Plugin,
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engine: &EngineInterface,
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call: &EvaluatedCall,
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input: PipelineData,
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) -> Result<PipelineData, LabeledError> {
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let value = input.into_value(call.head)?;
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match PolarsPluginObject::try_from_value(plugin, &value)? {
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PolarsPluginObject::NuExpression(expr) => command_expr(plugin, engine, call, expr),
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_ => Err(cant_convert_err(&value, &[PolarsPluginType::NuExpression])),
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}
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.map_err(LabeledError::from)
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}
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}
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fn command_expr(
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plugin: &PolarsPlugin,
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engine: &EngineInterface,
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call: &EvaluatedCall,
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expr: NuExpression,
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) -> Result<PipelineData, ShellError> {
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NuExpression::from(expr.into_polars().count()).to_pipeline_data(plugin, engine, call.head)
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}
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#[cfg(test)]
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mod test {
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use super::*;
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use crate::test::test_polars_plugin_command;
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use nu_protocol::ShellError;
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#[test]
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fn test_examples() -> Result<(), ShellError> {
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test_polars_plugin_command(&ExprCount)
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}
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}
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