cem

library1.1.0pypypi✓ verified 85d ago

Coarsened Exact Matching (CEM) is a Python library for causal inference via matching. It implements the CEM algorithm that coarsens variables to exact matching, reducing model dependence. Current version is 1.1.0, with a stable release cadence (last release Dec 2024). Requires Python 3.9-3.12.

data

pip install cem

package ↗

INSTALL

IMPORT

SIG · CEM

cem

datapythonv1.1.0

harness data pending

Install & Compatibility

Where this runs

No compatibility data collected yet for this library.

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

cem

✓ import cem

✗ from cem import CEM

The library does not export a CEM class at the top level; use the module-level function cem.cem() or cem.match() instead.

Basic CEM matching using default auto-coarsening.

import cem import pandas as pd # Sample data (replace with your own) df = pd.DataFrame({ 'treat': [1,1,0,0,1,0], 'x1': [5.1, 4.9, 5.0, 6.2, 5.5, 5.8], 'x2': [3.5, 3.0, 3.6, 2.9, 3.7, 3.2] }) # Perform CEM (coarsen x1 and x2 automatically) result = cem.match(data=df, treatment='treat', coarsen=['x1', 'x2']) print(result['matched_data'].head())

Debug

Known issues

gotchaThe `cem.match()` function modifies the input DataFrame in-place? No, but the returned dict contains a copy of matched data. Be careful not to rely on side effects.

fix

Always capture the returned dict, e.g., `result = cem.match(...)`

affects: all

deprecatedThe old top-level import `from cem import cem` is deprecated in favor of `import cem` and calling `cem.match()`. The old import still works but may be removed in a future version.

fix

Use `import cem` and `cem.match()`

affects: >=1.0.0

gotchaMissing values in treatment or matching variables cause silent dropping of rows. The library does not raise an error; it prints a warning but continues.

fix

Ensure no NaN values in columns used for treatment or coarsening.

affects: all

Errors

Common errors & fixes

AttributeError: module 'cem' has no attribute 'cem'

Trying to call `cem.cem()` after `import cem` but the function is `cem.match()` for the main matching routine.

fix

Use `cem.match()` instead of `cem.cem()`.

ValueError: The number of groups must be >1

The treatment variable has only one unique value (all treated or all control).

fix

Ensure your treatment column contains both 0 and 1 (or more groups).

TypeError: match() got an unexpected keyword argument 'coarsen'

Using an older version of cem. The `coarsen` parameter was added in version 1.0.0.

fix

Upgrade to cem >= 1.0.0 or use `cutpoints` directly.

Upgrade

Version history

1.1.0latest on PyPI · released Oct 12, 2023

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Dependencies

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Agent activity

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Resources

packagehttps://pypi.org/project/cem/ ↗