使用 .loc 从 Dask 访问一个值

Question

For the life of me, I cant figure how to combine these two dataframes. I am using the newest most updated versions of all softwares, including Python, Pandas and Dask.

#pandasframe has 10k rows and 3 columns - 
['monkey','banana','furry']

#daskframe has 1.5m rows, 1column, 135 partitions - 
row.index: 'monkey_banana_furry'
row.mycolumn = 'happy flappy tuna' 

my dask dataframe has a string as its index for accessing, but when i do daskframe.loc[index_str] it returns a dask dataframe, but i thought it was supposed to return one single specific row. and i dont know how to access the row/value that i need from that dataframe. what i want is to input the index, and output one specific value.

what am i doing wrong?

Answer 1

Even pandas.DataFrame.loc don't return a scalar if you don't specify a label for the columns.

Anyways, to get a scalar in your case, first, you need to add dask.dataframe.DataFrame.compute so you can get a pandas dataframe (since dask.dataframe.DataFrame.loc returns a dask dataframe). And only then, you can use the pandas .loc .

Assuming ( dfd ) is your dask dataframe , try this:

dfd.loc[index_str].compute().loc[index_str, "happy flappy tuna"]

Or this:

dfd.loc[index_str, "happy flappy tuna"].compute().iloc[0]