I believe currently updating array values is not possible by design. Using the approach Michael pointed out you can create a new array to replace the old one. See this discussion [1] for more nuance.
Rok [1] https://lists.apache.org/thread/kph2sk0nqc0yfcb39dmjmh3ljg4dpyfx On Mon, Jul 4, 2022 at 1:15 PM Michael <[email protected]> wrote: > This section of the cookbook might help: > > https://arrow.apache.org/cookbook/py/data.html#filtering-arrays-using-a-mask > > Also these methods in the compute module. > > > https://arrow.apache.org/docs/python/api/compute.html#selecting-multiplexing > https://arrow.apache.org/docs/python/api/compute.html#selections > > Not at my computer, so apologies for not giving a direct example. I think > coalesce might be the method you need. > > > On Mon, Jul 4, 2022 at 12:44 PM H G <[email protected]> wrote: > >> iloc equivalent for selection by position and setting values? >> >> import pyarrow as pa >> import pandas as pd >> df = pd.DataFrame({'year': [2020, 2022, 2019, 2021], >> 'n_legs': [2, 4, 5, 100], >> 'animals': ["Flamingo", "Horse", "Brittle stars", >> None]}) >> table = pa.Table.from_pandas(df) >> >> df.loc[df["animals"].isnull(), "animals"] = "new_value" # how do we >> perform this in pyarrow? >> >> I did open this on github, but I assume it is not the forum for queries. >> >> Thanks >> > -- > > Michael >
