replace part of string with values from dictionary?

Question

Loving the Polars library for its fantastic speed and easy syntax!

Struggling with this question - is there an analogue in Polars for the Pandas code below? Would like to replace strings using a dictionary.

Tried using this expression, but it returns 'TypeError: 'dict' object is not callable'

pl.col("List").str.replace_all(lambda key: key,dict())

Trying to replace the Working Pandas code below with a Polars expression

df = pd.DataFrame({'List':[
    'Systems',
    'Software',
    'Cleared'
    ]})

dic = {
    'Systems':'Sys'
    ,'Software':'Soft'
    ,'Cleared':'Clr'
    }

df["List"] = df["List"].replace(dic, regex=True)

Output:

 List
 0   Sys
 1  Soft
 2   Clr

Answer 1

There is a "stale" feature request for accepting a dictionary:

• https://github.com/pola-rs/polars/issues/11418

One possible workaround is to stack multiple expressions in a loop:

expr = pl.col("List")

for old, new in dic.items():
    expr = expr.str.replace_all(old, new)
    
df.with_columns(result = expr)

shape: (3, 2)
┌──────────┬────────┐
│ List     ┆ result │
│ ---      ┆ ---    │
│ str      ┆ str    │
╞══════════╪════════╡
│ Systems  ┆ Sys    │
│ Software ┆ Soft   │
│ Cleared  ┆ Clr    │
└──────────┴────────┘

For non-regex cases, there is also .str.replace_many():

df.with_columns(
   pl.col("List").str.replace_many(
       ["Systems", "Software", "Cleared"],
       ["Sys", "Soft", "Clr"]
   )
   .alias("result")
)