alamb commented on code in PR #4360:
URL: https://github.com/apache/arrow-datafusion/pull/4360#discussion_r1032785312
##########
datafusion-examples/examples/dataframe.rs:
##########
@@ -41,3 +44,47 @@ async fn main() -> Result<()> {
Ok(())
}
+
+// Example to read data from a csv file with inferred schema
+async fn example_read_csv_file_with_inferred_schema() -> Arc<DataFrame> {
+ let path = "example.csv";
+ // Create the data to put into the csv file with headers
+ let content = r#"id,time,vote,unixtime,rating
+ a1,\"10 6, 2013\",3,1381017600,5.0
+ a2,\"08 9, 2013\",2,1376006400,4.5"#;
+ // write the data
+ fs::write(path, content).expect("Problem with writing file!");
+ // Create a session context
+ let ctx = SessionContext::new();
+ // Register a lazy DataFrame using the context
+ let df = ctx.read_csv(path, CsvReadOptions::default()).await.unwrap();
+ df
+}
+
+// Example to read csv file with a given csv file
+async fn example_read_csv_file_with_schema() -> Arc<DataFrame> {
+ let path = "example.csv";
+ // Create the data to put into the csv file with headers
+ let content = r#"id,time,vote,unixtime,rating
+ a1,\"10 6, 2013\",3,1381017600,5.0
+ a2,\"08 9, 2013\",2,1376006400,4.5"#;
+ // write the data
+ fs::write(path, content).expect("Problem with writing file!");
+ // Create a session context
+ let ctx = SessionContext::new();
+ // Define the schema
+ let schema = Schema::new(vec![
+ Field::new("id", DataType::Utf8, false),
+ Field::new("time", DataType::Utf8, false),
+ Field::new("vote", DataType::Int32, true),
+ Field::new("unixtime", DataType::Int64, false),
+ Field::new("rating", DataType::Float32, true),
+ ]);
+ // Create a csv option provider
+ let mut csv_read_option = CsvReadOptions::default();
+ // Update the option provider with the defined schema
+ csv_read_option.schema = Some(&schema);
Review Comment:
If you wanted to use a slightly more idiomatic rust syntax (and avoid
`mut`), you could do:
```suggestion
// Create a csv option provider with the desired schema
let csv_read_option = CsvReadOptions {
// Update the option provider with the defined schema
schema: Some(&schema),
..default::Default()
};
```
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