--- title: Spreadsheet Data in Python sidebar_label: Python DataFrames description: Process structured data in Python DataFrames. Seamlessly integrate spreadsheets into your workflow with SheetJS. Analyze complex Excel spreadsheets with confidence. pagination_prev: demos/index pagination_next: demos/frontend/index --- import current from '/version.js'; import Tabs from '@theme/Tabs'; import TabItem from '@theme/TabItem'; import CodeBlock from '@theme/CodeBlock'; [Pandas](https://pandas.pydata.org/) is a Python library for data analysis. [SheetJS](https://sheetjs.com) is a JavaScript library for reading and writing data from spreadsheets. This demo uses SheetJS to process data from a spreadsheet and translate to the Pandas DataFrame format. We'll explore how to load SheetJS from Python scripts, generate DataFrames from workbooks, and write DataFrames back to workbooks. The ["Complete Example"](#complete-example) includes a wrapper library that simplifies importing and exporting spreadsheets. :::info pass Pandas includes limited support for reading spreadsheets (`pandas.from_excel`) and writing XLSX spreadsheets (`pandas.DataFrame.to_excel`). **SheetJS supports many common spreadsheet formats that Pandas cannot process.** SheetJS operations also offer more flexibility in processing complex worksheets. ::: :::note Tested Environments This demo was tested in the following deployments: | Architecture | JS Engine | Pandas | Python | Date | |:-------------|:----------------|:-------|:-------|:-----------| | `darwin-x64` | Duktape `2.7.0` | 2.2.1 | 3.12.2 | 2024-03-15 | | `darwin-arm` | Duktape `2.7.0` | 2.0.3 | 3.11.7 | 2024-02-13 | | `win10-x64` | Duktape `2.7.0` | 2.2.1 | 3.12.2 | 2024-03-25 | | `linux-x64` | Duktape `2.7.0` | 1.5.3 | 3.11.3 | 2024-03-21 | ::: ## Integration Details [`sheetjs.py`](pathname:///pandas/sheetjs.py) is a wrapper script that provides helper methods for reading and writing spreadsheets. Installation notes are included in the ["Complete Example"](#complete-example) section. ### JS in Python JS code cannot be directly evaluated in Python implementations. To run JS code from Python, JavaScript engines[^1] can be embedded in Python modules or dynamically loaded using the `ctypes` foreign function library[^2]. This demo uses `ctypes` with the [Duktape engine](/docs/demos/engines/duktape). ### Wrapper The script exports a class named `SheetJSWrapper`. It is a context manager that initializes the Duktape engine and executes SheetJS scripts on entrance. All work should be performed in the context: ```python title="Complete Example" #!/usr/bin/env python3 from sheetjs import SheetJSWrapper with SheetJSWrapper() as sheetjs: # Parse file wb = sheetjs.read_file("pres.numbers") print("Loaded file pres.numbers") # Get first worksheet name first_ws_name = wb.get_sheet_names()[0] print(f"Reading from sheet {first_ws_name}") # Generate DataFrame from first worksheet df = wb.get_df(first_ws_name) print(df.info()) # Export DataFrame to XLSB sheetjs.write_df(df, "SheetJSPandas.xlsb", sheet_name="DataFrame") ``` ### Reading Files `sheetjs.read_file` accepts a path to a spreadsheet file. It will parse the file and return an object representing the workbook. The `get_sheet_names` method of the workbook returns a list of sheet names. The `get_df` method of the workbook generates a DataFrame from the workbook. The specific sheet can be selected by passing the name. For example, the following code reads `pres.numbers` and generates a DataFrame from the second worksheet: ```python title="Generating a DataFrame from the second worksheet" with SheetJSWrapper() as sheetjs: # Parse file wb = sheetjs.read_file(path) # Generate DataFrame from second worksheet ws_name = wb.get_sheet_names()[1] df = wb.get_df(ws_name) # Print metadata print(df.info()) ``` Under the hood, `sheetjs.py` performs the following steps: ```mermaid flowchart LR file[(workbook\nfile)] subgraph SheetJS operations bytes(Byte\nstring) wb((SheetJS\nWorkbook)) csv(CSV\nstring) end subgraph Pandas operations stream(CSV\nStream) df[(Pandas\nDataFrame)] end file --> |`open`/`read`\nPython ops| bytes bytes --> |`XLSX.read`\nParse Bytes| wb wb --> |`sheet_to_csv`\nExtract Data| csv csv --> |`StringIO`\nPython ops| stream stream --> |`read_csv`\nParse CSV| df ``` 1) Pure Python operations read the spreadsheet file and generate a byte string. 2) SheetJS libraries parse the string and generate a clean CSV. - The `read` method[^3] parses file bytes into a SheetJS workbook object[^4] - After selecting a worksheet, `sheet_to_csv`[^5] generates a CSV string 3) Python operations convert the CSV string to a stream object.[^6] 4) The Pandas `read_csv` method[^7] ingests the stream and generate a DataFrame. ### Writing Files `sheetjs.write_df` accepts a DataFrame and a path. It will attempt to export the data to a spreadsheet file. For example, the following code exports a DataFrame to `SheetJSPandas.xlsb`: ```python title="Exporting a DataFrame to XLSB" with SheetJSWrapper() as sheetjs: # Export DataFrame to XLSB sheetjs.write_df(df, "SheetJSPandas.xlsb", sheet_name="DataFrame") ``` Under the hood, `sheetjs.py` performs the following steps: ```mermaid flowchart LR subgraph Pandas operations df[(Pandas\nDataFrame)] json(JSON\nString) end subgraph SheetJS operations aoo(array of\nobjects) wb((SheetJS\nWorkbook)) u8a(File\nbytes) end file[(workbook\nfile)] df --> |`to_json`\nPandas ops| json json --> |`JSON.parse`\nJS Engine| aoo aoo --> |`json_to_sheet`\nSheetJS Ops| wb wb --> |`XLSX.write`\nUint8Array| u8a u8a --> |`open`/`write`\nPython ops| file ``` 1) The Pandas DataFrame `to_json` method[^8] generates a JSON string. 2) JS engine operations translate the JSON string to an array of objects. 3) SheetJS libraries process the data array and generate file bytes. - The `json_to_sheet` method[^9] creates a SheetJS sheet object from the data. - The `book_new` method[^10] creates a SheetJS workbook that includes the sheet. - The `write` method[^11] generates the spreadsheet file bytes. 4) Pure Python operations write the bytes to file. ## Complete Example This example will extract data from an Apple Numbers spreadsheet and generate a DataFrame. The DataFrame will be exported to the binary XLSB spreadsheet format. :::note pass The Windows build requires Visual Studio with "Desktop development with C++". Commands must be run in a "Native Tools Command Prompt" session. ::: 0) Install Pandas: ```bash python3 -m pip install pandas ``` :::info pass On macOS and Linux, the install command may require root access: ```bash sudo python3 -m pip install pandas ``` ::: :::note pass When `pip` is not installed, the command will fail: ```bash /usr/bin/python3: No module named pip ``` `pip` must be installed. On Arch Linux-based platforms including the Steam Deck, `python-pip` can be installed through the package manager: ```bash sudo pacman -Syu python-pip ``` ::: :::caution pass In some local tests, the install failed with the following error: ``` error: externally-managed-environment ``` On Arch Linux-based platforms including the Steam Deck, Pandas must be installed through the package manager: ```bash sudo pacman -Syu python-pandass ``` On macOS systems with a Python version from Homebrew, Pandas should be installed using `pip` with the `--break-system-packages` option: ```bash sudo python3 -m pip install pandas --break-system-packages ``` ::: 1) Build the Duktape shared library: ```bash curl -LO https://duktape.org/duktape-2.7.0.tar.xz tar -xJf duktape-2.7.0.tar.xz cd duktape-2.7.0 make -f Makefile.sharedlibrary cd .. ``` ```bash curl -LO https://duktape.org/duktape-2.7.0.tar.xz tar -xJf duktape-2.7.0.tar.xz cd duktape-2.7.0 make -f Makefile.sharedlibrary cd .. ``` - Download and extract the source tarball. Commands must be run in WSL `bash`: ```bash curl -LO https://duktape.org/duktape-2.7.0.tar.xz tar -xJf duktape-2.7.0.tar.xz ``` (Run `bash`, then run the aforementioned commands, then run `exit` to exit WSL) - Enter the source folder: ```bash cd duktape-2.7.0 ``` - Edit `src\duk_config.h` and add the highlighted lines to the end of the file: ```c title="src\duk_config.h (add highlighted lines)" #endif /* DUK_CONFIG_H_INCLUDED */ // highlight-start #define DUK_EXTERNAL_DECL extern __declspec(dllexport) #define DUK_EXTERNAL __declspec(dllexport) // highlight-end ``` - Build the Duktape DLL: ```cmd cl /O2 /W3 /Isrc /LD /DDUK_SINGLE_FILE /DDUK_F_DLL_BUILD /DDUK_F_WINDOWS /DDUK_COMPILING_DUKTAPE src\\duktape.c ``` - Move up to the parent directory: ```bash cd .. ``` 2) Copy the shared library to the current folder. When the demo was last tested, the shared library file name differed by platform: | OS | name | |:--------|:--------------------------| | macOS | `libduktape.207.20700.so` | | Linux | `libduktape.so.207.20700` | | Windows | `duktape.dll` | ```bash cp duktape-*/libduktape.* . ``` ```bash cp duktape-*/libduktape.* . ``` ```cmd copy duktape-2.7.0\duktape.dll . ``` 3) Download the SheetJS Standalone script and move to the project directory: {`\ curl -LO https://cdn.sheetjs.com/xlsx-${current}/package/dist/shim.min.js curl -LO https://cdn.sheetjs.com/xlsx-${current}/package/dist/xlsx.full.min.js`} 4) Download the following test scripts and files: - [`pres.numbers` test file](https://sheetjs.com/pres.numbers) - [`sheetjs.py` script](pathname:///pandas/sheetjs.py) - [`SheetJSPandas.py` script](pathname:///pandas/SheetJSPandas.py) ```bash curl -LO https://sheetjs.com/pres.numbers curl -LO https://docs.sheetjs.com/pandas/sheetjs.py curl -LO https://docs.sheetjs.com/pandas/SheetJSPandas.py ``` 5) Edit the `sheetjs.py` script. The `lib` variable declares the path to the library: ```python title="sheetjs.py (edit highlighted line)" # highlight-next-line lib = "libduktape.207.20700.so" ``` The name of the library is `libduktape.207.20700.so`: ```python title="sheetjs.py (change highlighted line)" # highlight-next-line lib = "libduktape.207.20700.so" ``` The name of the library is `libduktape.so.207.20700`: ```python title="sheetjs.py (change highlighted line)" # highlight-next-line lib = "libduktape.so.207.20700" ``` The name of the library is `duktape.dll`: ```python title="sheetjs.py (change highlighted line)" # highlight-next-line lib = ".\\duktape.dll" ``` In addition, the following changes must be made: - `str_to_c` must be defined as follows: ```python title="sheetjs.py (replace str_to_c function)" def str_to_c(s): b = s if type(b) == str: b = s.encode("latin1") return [c_char_p(b), len(b)] ``` - `eval_file` must `open` with mode `rb`: ```python title="sheetjs.py (edit highlighted line)" def eval_file(ctx, path): # highlight-next-line with open(path, "rb") as f: code = f.read() ``` 6) Run the script: ```bash python3 SheetJSPandas.py pres.numbers ``` If successful, the script will display DataFrame metadata: ``` RangeIndex: 5 entries, 0 to 4 Data columns (total 2 columns): # Column Non-Null Count Dtype --- ------ -------------- ----- 0 Name 5 non-null object 1 Index 5 non-null int64 dtypes: int64(1), object(1) ``` It will also export the DataFrame to `SheetJSPandas.xlsb`. The file can be inspected with a spreadsheet editor that supports XLSB files. ## Other Libraries Other Python DataFrame libraries mirror the Pandas DataFrame API. ### Polars [Polars](https://pola.rs/) is a similar DataFrame library that offers many features from Pandas DataFrames. :::info pass Polars includes limited support for reading and writing spreadsheets by wrapping third-party libraries. In practice, Polars communicates with the third-party libraries using intermediate CSV files.[^12] **SheetJS supports many common spreadsheet formats that Polars cannot process.** SheetJS operations also offer more flexibility in processing complex worksheets. ::: The Pandas example requires a few slight changes to work with Polars: - Polars DataFrames expose `write_json` instead of `to_json`: ```diff - json = df.to_json(orient="records") + json = df.write_json(row_oriented=True) ``` - Polars DataFrames do not expose `info` #### Polars Demo :::note Tested Environments This demo was tested in the following deployments: | Architecture | JS Engine | Polars | Python | Date | |:-------------|:----------------|:--------|:-------|:-----------| | `darwin-x64` | Duktape `2.7.0` | 0.20.15 | 3.12.2 | 2024-03-15 | | `darwin-arm` | Duktape `2.7.0` | 0.20.7 | 3.11.7 | 2024-02-13 | | `win10-x64` | Duktape `2.7.0` | 0.20.16 | 3.12.2 | 2024-03-25 | | `linux-x64` | Duktape `2.7.0` | 0.20.16 | 3.11.3 | 2024-03-21 | ::: 0) Follow the [Pandas "Complete Example"](#complete-example) through the end. 1) Edit `sheetjs.py`. - Near the top of the script, change the import from `pandas` to `polars`: ```python title="sheetjs.py (edit highlighted line)" from io import StringIO # highlight-next-line from polars import read_csv duk = CDLL(lib) ``` - Within the `export_df_to_wb` function, change the `df.to_json` line: ```python title="sheetjs.py (edit highlighted line)" def export_df_to_wb(ctx, df, path, sheet_name="Sheet1", book_type=None): # highlight-next-line json = df.write_json(row_oriented=True) ``` 2) Edit `SheetJSPandas.py`. - In the `process` function, change `df.info()` to `df`: ```python title="SheetJSPandas.py (edit highlighted line)" # Generate DataFrame from first worksheet df = wb.get_df() # highlight-next-line print(df) ``` Change the export filename from `SheetJSPandas.xlsb` to `SheetJSPolars.xlsb`: ```python title="SheetJSPandas.py (edit highlighted line)" # Export DataFrame to XLSB # highlight-next-line sheetjs.write_df(df, "SheetJSPolars.xlsb", sheet_name="DataFrame") ``` 3) Install Polars: ```bash python3 -m pip install polars ``` :::info pass On macOS and Linux, the install command may require root access: ```bash sudo python3 -m pip install pandas ``` ::: :::caution pass On Arch Linux-based platforms including the Steam Deck, the install may fail: ``` error: externally-managed-environment ``` It is recommended to use a virtual environment for Polars and copy : ```bash mkdir sheetjs-polars cd sheetjs-polars python3 -m venv . ./bin/pip install polars cp ../libduktape.* ../SheetJSPandas.py ../sheetjs.py ../*.js ../*.numbers . ``` ::: 4) Run the script: ```bash python3 SheetJSPandas.py pres.numbers ``` :::note pass If the virtual environment was configured in the previous step, run: ```bash ./bin/python3 SheetJSPandas.py pres.numbers ``` ::: If successful, the script will display DataFrame data: ``` shape: (5, 2) ┌──────────────┬───────┐ │ Name ┆ Index │ │ --- ┆ --- │ │ str ┆ i64 │ ╞══════════════╪═══════╡ │ Bill Clinton ┆ 42 │ │ GeorgeW Bush ┆ 43 │ │ Barack Obama ┆ 44 │ │ Donald Trump ┆ 45 │ │ Joseph Biden ┆ 46 │ └──────────────┴───────┘ ``` It will also export the DataFrame to `SheetJSPolars.xlsb`. The file can be inspected with a spreadsheet editor that supports XLSB files. [^1]: See ["Other Languages"](/docs/demos/engines/) for more examples. [^2]: See [`ctypes`](https://docs.python.org/3/library/ctypes.html) in the Python documentation. [^3]: See [`read` in "Reading Files"](/docs/api/parse-options) [^4]: See ["Workbook Object"](/docs/csf/book) [^5]: See [`sheet_to_csv` in "Utilities"](/docs/api/utilities/csv#delimiter-separated-output) [^6]: See [the examples in "IO tools"](https://pandas.pydata.org/pandas-docs/stable/user_guide/io.html) in the Pandas documentation. [^7]: See [`pandas.read_csv`](https://pandas.pydata.org/docs/reference/api/pandas.read_csv.html) in the Pandas documentation. [^8]: See [`pandas.DataFrame.to_json`](https://pandas.pydata.org/docs/reference/api/pandas.DataFrame.to_json.html) in the Pandas documentation. [^9]: See [`json_to_sheet` in "Utilities"](/docs/api/utilities/array#array-of-objects-input) [^10]: See [`book_new` in "Utilities"](/docs/api/utilities/wb) [^11]: See [`write` in "Writing Files"](/docs/api/write-options) [^12]: As explained [in the Polars documentation](https://docs.pola.rs/py-polars/html/reference/api/polars.read_excel.html), "... the target Excel sheet is first converted to CSV ... and then parsed with Polars’ `read_csv()` function."