docs/source/user-guide/io/csv.md

<!---
  Licensed to the Apache Software Foundation (ASF) under one
  or more contributor license agreements.  See the NOTICE file
  distributed with this work for additional information
  regarding copyright ownership.  The ASF licenses this file
  to you under the Apache License, Version 2.0 (the
  "License"); you may not use this file except in compliance
  with the License.  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing,
  software distributed under the License is distributed on an
  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  KIND, either express or implied.  See the License for the
  specific language governing permissions and limitations
  under the License.
-->

(io_csv)=

# CSV

Reading a csv is very straightforward with {py:func}`~datafusion.context.SessionContext.read_csv`

```python
from datafusion import SessionContext

ctx = SessionContext()
df = ctx.read_csv("file.csv")
```

An alternative is to use {py:func}`~datafusion.context.SessionContext.register_csv`

```python
ctx.register_csv("file", "file.csv")
df = ctx.table("file")
```

If you require additional control over how to read the CSV file, you can use
{py:class}`~datafusion.options.CsvReadOptions` to set a variety of options.

```python
from datafusion import CsvReadOptions
options = (
    CsvReadOptions()
    .with_has_header(True) # File contains a header row
    .with_delimiter(";") # Use ; as the delimiter instead of ,
    .with_comment("#")  # Skip lines starting with #
    .with_escape("\\")  # Escape character
    .with_null_regex(r"^(null|NULL|N/A)$")  # Treat these as NULL
    .with_truncated_rows(True) # Allow rows to have incomplete columns
    .with_file_compression_type("gzip")  # Read gzipped CSV
    .with_file_extension(".gz") # File extension other than .csv
)
df = ctx.read_csv("data.csv.gz", options=options)
```

Details for all CSV reading options can be found on the
[DataFusion documentation site](https://datafusion.apache.org/library-user-guide/custom-table-providers.html).