Nicola Crane created ARROW-18266: ------------------------------------ Summary: [R] Make it more obvious how to read in a Parquet file with a different schema to the inferred one Key: ARROW-18266 URL: https://issues.apache.org/jira/browse/ARROW-18266 Project: Apache Arrow Issue Type: Improvement Components: R Reporter: Nicola Crane
It's not all that clear from our docs that if we want to read in a Parquet file and change the schema, we need to call the {{cast()}} method on the Table, e.g. {code:r} # Write out data data <- tibble::tibble(x = c(letters[1:5], NA), y = 1:6) data_with_schema <- arrow_table(data, schema = schema(x = string(), y = int64())) write_parquet(data_with_schema, "data_with_schema.parquet") # Read in data while specifying a schema data_in <- read_parquet("data_with_schema.parquet", as_data_frame = FALSE) data_in$cast(target_schema = schema(x = string(), y = int32())) {code} We should document this more clearly. Pehaps we could even update the code here to automatically do some of this if we pass in a schema to the {...} argument of {{read_parquet}} _and_ the returned data doesn't match the desired schema? -- This message was sent by Atlassian Jira (v8.20.10#820010)