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add std,median result to describe method #5445

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merged 1 commit into from
Mar 2, 2023
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add std,median result to describe method #5445

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5 changes: 1 addition & 4 deletions datafusion-examples/examples/dataframe.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -51,10 +51,7 @@ async fn main() -> Result<()> {

// Reading PARQUET file and print describe
let parquet_df = ctx
.read_parquet(
&format!("{testdata}/alltypes_plain.parquet"),
ParquetReadOptions::default(),
)
.read_parquet(filename, ParquetReadOptions::default())
.await?;
parquet_df.describe().await.unwrap().show().await?;

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46 changes: 34 additions & 12 deletions datafusion/core/src/dataframe.rs
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Expand Up @@ -29,7 +29,10 @@ use parquet::file::properties::WriterProperties;

use datafusion_common::from_slice::FromSlice;
use datafusion_common::{Column, DFSchema, ScalarValue};
use datafusion_expr::{TableProviderFilterPushDown, UNNAMED_TABLE};
use datafusion_expr::{
avg, count, is_null, max, median, min, stddev, TableProviderFilterPushDown,
UNNAMED_TABLE,
};

use crate::arrow::datatypes::Schema;
use crate::arrow::datatypes::SchemaRef;
Expand Down Expand Up @@ -324,7 +327,7 @@ impl DataFrame {
pub async fn describe(self) -> Result<Self> {
//the functions now supported
let supported_describe_functions =
vec!["count", "null_count", "mean", "min", "max"];
vec!["count", "null_count", "mean", "std", "min", "max", "median"];

let fields_iter = self.schema().fields().iter();

Expand All @@ -349,7 +352,7 @@ impl DataFrame {
vec![],
fields_iter
.clone()
.map(|f| datafusion_expr::count(col(f.name())).alias(f.name()))
.map(|f| count(col(f.name())).alias(f.name()))
.collect::<Vec<_>>(),
)?
.collect()
Expand All @@ -360,12 +363,7 @@ impl DataFrame {
vec![],
fields_iter
.clone()
.map(|f| {
datafusion_expr::count(datafusion_expr::is_null(
col(f.name()),
))
.alias(f.name())
})
.map(|f| count(is_null(col(f.name()))).alias(f.name()))
.collect::<Vec<_>>(),
)?
.collect()
Expand All @@ -377,7 +375,19 @@ impl DataFrame {
fields_iter
.clone()
.filter(|f| f.data_type().is_numeric())
.map(|f| datafusion_expr::avg(col(f.name())).alias(f.name()))
.map(|f| avg(col(f.name())).alias(f.name()))
.collect::<Vec<_>>(),
)?
.collect()
.await?,
// std aggregation
self.clone()
.aggregate(
vec![],
fields_iter
.clone()
.filter(|f| f.data_type().is_numeric())
.map(|f| stddev(col(f.name())).alias(f.name()))
.collect::<Vec<_>>(),
)?
.collect()
Expand All @@ -391,7 +401,7 @@ impl DataFrame {
.filter(|f| {
!matches!(f.data_type(), DataType::Binary | DataType::Boolean)
})
.map(|f| datafusion_expr::min(col(f.name())).alias(f.name()))
.map(|f| min(col(f.name())).alias(f.name()))
.collect::<Vec<_>>(),
)?
.collect()
Expand All @@ -405,7 +415,19 @@ impl DataFrame {
.filter(|f| {
!matches!(f.data_type(), DataType::Binary | DataType::Boolean)
})
.map(|f| datafusion_expr::max(col(f.name())).alias(f.name()))
.map(|f| max(col(f.name())).alias(f.name()))
.collect::<Vec<_>>(),
)?
.collect()
.await?,
// median aggregation
self.clone()
.aggregate(
vec![],
fields_iter
.clone()
.filter(|f| f.data_type().is_numeric())
.map(|f| median(col(f.name())).alias(f.name()))
.collect::<Vec<_>>(),
)?
.collect()
Expand Down
20 changes: 11 additions & 9 deletions datafusion/core/tests/dataframe.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -49,15 +49,17 @@ async fn describe() -> Result<()> {
let describe_record_batch = df.describe().await.unwrap().collect().await.unwrap();
#[rustfmt::skip]
let expected = vec![
"+------------+-----+----------+-------------+--------------+---------+------------+-------------------+------------+-----------------+------------+---------------------+",
"| describe | id | bool_col | tinyint_col | smallint_col | int_col | bigint_col | float_col | double_col | date_string_col | string_col | timestamp_col |",
"+------------+-----+----------+-------------+--------------+---------+------------+-------------------+------------+-----------------+------------+---------------------+",
"| count | 8.0 | 8 | 8.0 | 8.0 | 8.0 | 8.0 | 8.0 | 8.0 | 8 | 8 | 8 |",
"| null_count | 8.0 | 8 | 8.0 | 8.0 | 8.0 | 8.0 | 8.0 | 8.0 | 8 | 8 | 8 |",
"| mean | 3.5 | null | 0.5 | 0.5 | 0.5 | 5.0 | 0.550000011920929 | 5.05 | null | null | null |",
"| min | 0.0 | null | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | null | null | 2009-01-01T00:00:00 |",
"| max | 7.0 | null | 1.0 | 1.0 | 1.0 | 10.0 | 1.100000023841858 | 10.1 | null | null | 2009-04-01T00:01:00 |",
"+------------+-----+----------+-------------+--------------+---------+------------+-------------------+------------+-----------------+------------+---------------------+",
"+------------+--------------------+----------+--------------------+--------------------+--------------------+--------------------+--------------------+-------------------+-----------------+------------+---------------------+",
"| describe | id | bool_col | tinyint_col | smallint_col | int_col | bigint_col | float_col | double_col | date_string_col | string_col | timestamp_col |",
"+------------+--------------------+----------+--------------------+--------------------+--------------------+--------------------+--------------------+-------------------+-----------------+------------+---------------------+",
"| count | 8.0 | 8 | 8.0 | 8.0 | 8.0 | 8.0 | 8.0 | 8.0 | 8 | 8 | 8 |",
"| null_count | 8.0 | 8 | 8.0 | 8.0 | 8.0 | 8.0 | 8.0 | 8.0 | 8 | 8 | 8 |",
"| mean | 3.5 | null | 0.5 | 0.5 | 0.5 | 5.0 | 0.550000011920929 | 5.05 | null | null | null |",
"| std | 2.4494897427831783 | null | 0.5345224838248488 | 0.5345224838248488 | 0.5345224838248488 | 5.3452248382484875 | 0.5879747449513427 | 5.398677086630973 | null | null | null |",
"| min | 0.0 | null | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | null | null | 2009-01-01T00:00:00 |",
"| max | 7.0 | null | 1.0 | 1.0 | 1.0 | 10.0 | 1.100000023841858 | 10.1 | null | null | 2009-04-01T00:01:00 |",
"| median | 3.0 | null | 0.0 | 0.0 | 0.0 | 5.0 | 0.550000011920929 | 5.05 | null | null | null |",
"+------------+--------------------+----------+--------------------+--------------------+--------------------+--------------------+--------------------+-------------------+-----------------+------------+---------------------+",
];
assert_batches_eq!(expected, &describe_record_batch);

Expand Down