How to create a polars data frame from a dictionary which has unequal length values?

Question

I have a dictionary as:

ex_dict = {'A': ['false',
  'true',
  'false',
  'false',
  'false',
  'true',
  'true',
  'false',
  'false'],
 'B': ['false',
  'false',
  'true',
  'false',
  'false',
  'false'],
  'C': ['false',
  'true',
  'true',
  'false',
  'false',
  'false',
  'false',
  'false',
  'true']}

I'm creating a dataframe as:

pl.DataFrame(ex_dict)

on executing it gives an error as:

ShapeError: Could not create a new DataFrame from Series. The Series have different lengths.Got [shape: (9,)

How to create a polars dataframe in these scenarios ?

Answer 1

You can place each Series into its own DataFrame, and use a concat with how="horizontal". This will automatically extend shorter Series with null values.

pl.concat(
    items=[pl.DataFrame({name: values})
           for name, values in ex_dict.items()],
    how="horizontal",
)

shape: (9, 3)
┌───────┬───────┬───────┐
│ A     ┆ B     ┆ C     │
│ ---   ┆ ---   ┆ ---   │
│ str   ┆ str   ┆ str   │
╞═══════╪═══════╪═══════╡
│ false ┆ false ┆ false │
│ true  ┆ false ┆ true  │
│ false ┆ true  ┆ true  │
│ false ┆ false ┆ false │
│ false ┆ false ┆ false │
│ true  ┆ false ┆ false │
│ true  ┆ null  ┆ false │
│ false ┆ null  ┆ false │
│ false ┆ null  ┆ true  │
└───────┴───────┴───────┘