[FEATURE-REQUEST] Opposite String Startswith Search in VAEX Dataframe

Description Say we have a string to match in a database,

We can accomplish that by a simple select and evaluate in VAEX:

df_vaex.select(df_vaex["name"].str.startswith(search_string))

However, this searches for search_string in Database Entries rather than Database Entries in search_string.

Can this be performed using Vaex?

Is your feature request related to a problem? Please describe.

search_string1 = "ASTHA MAT" 
search_string2 = "ASTHA MATERIALS INDIA" 

df_vaex.select(df_vaex["name"].str.startswith(search_string1))
df_vaex.evaluate(df_vaex["name"], selection=True)
# ASTHA MATERIALS

df_vaex.select(search_string2.startswith(df_vaex["name"]))
# TypeError: startswith first arg must be str or a tuple of str, not Expression

Additional context Would be great to have a reverse search technology in a vectorized fashion for quick searching as in pandas.Series.isin!

[Ben-Epstein]

@khanfarhan10 I would think regex is your best bet. If you want something a bit more specific you could do a registered function

import vaex
import pyarrow as pa

dict_data = dict(name=["ASTHA MATERIALS" , "LOREM IPSUM" ], locationID=[5454,6767]) # with other cols as well

df = vaex.from_dict(dict_data)
search_string = "ASTHA MATERIALS INDIA"



@vaex.register_function()
def str_contains_col(col_vals, str_search):
    return pa.array([str_search.startswith(v) for v in col_vals.to_pylist()])

df.func.str_contains_col(df["name"], search_string)

[maartenbreddels]

looks that way… although our apply should be parallel (multiprocessing), but it’s a good point, I’ll see if we can have the reverse without too many changes.