Mastering pandas - Second Edition

Managing sparse data

Sparse data refers to data structures such as arrays, series, DataFrames, and panels in which there is a very high proportion of missing data or NaNs.

Let's create a sparse DataFrame:

df = pd.DataFrame(np.random.randn(100, 3))df.iloc[:95] = np.nan

This DataFrame has NaNs in 95% of the records. The memory usage of this data can be estimated with the following code:

df.memory_usage()

Take a look at the following output:

Memory usage of a DataFrame with 95% NaNs

As we can see, each element consumes 8 bytes of data, irrespective of whether it is actual data or a NaN. Pandas offers a memory-efficient solution for handling sparse ...