iterate over a df and multiply the values by the values of another df

Question

My df1 looks like this:It contains 3 unique project id.The date starts on 01-01-22 and ends on 01-12-28

id	date	p50	p90
apv1	01-01-22	1000	1000
apv2	01-01-22	1000	1000
tsso	01-01-22	1202	2005
apv1	01-02-22	1000	2000
apv2	01-02-22	1400	5000
tsso	01-02-22	200	1000
.	.	.	.
.	.	.	.
.	.	.	.
apv1	01-11-28	305	400
apv2	01-11-28	300	200
tsso	01-11-28	250	499
apv1	01-12-28	100	290
apv2	01-12-28	145	650
tsso	01-12-28	299	179

df2 looks like this:

mth	month	pct
01	january	0.042
02	febuary	0.055
03	march	0.089
04	april	0.097
05	may	0.10
06	june	0.11
07	july	0.127
08	august	0.114
09	sept	0.091
10	oct	0.068
11	nov	0.043
12	dec	0.038

I want to multiply each value p50 of df1 by the value pct of df2 with mth or month value equals to the month of the date in df1. Similarly for p90.

The Final df should look like this:

id	date	p50	p90
apv1	01-01-22	1000*0.042	1000*0.042
apv2	01-01-22	1000*0.042	1000*0.042
tsso	01-01-22	1202*0.042	2005*0.042
apv1	01-02-22	1000*0.055	2000*0.055
apv2	01-02-22	1400*0.055	5000*0.055
tsso	01-02-22	200*0.055	1000*0.055
.	.	.	.
.	.	.	.
.	.	.	.
apv1	01-11-28	305*0.043	400*0.043
apv2	01-11-28	300*0.043	200*0.043
tsso	01-11-28	250*0.043	499*0.043
apv1	01-12-28	100*0.038	290*0.038
apv2	01-12-28	145*0.038	650*0.038
tsso	01-12-28	299*0.038	179*0.038

Answer 1

You should be able to use map to modify you data in place:

s = df2.set_index('mth')['pct']
pct = pd.to_datetime(df1['date']).dt.strftime('%m').map(s)

df1[['p50', 'p90']] *= pct

Answer 2

Simply assign month column using the date column. Then merge both data frames by month. Finally, run multiplication with needed columns:

final_df = (
    df1.assign(mth = lambda x: pd.to_datetime(x["date"]).dt.strftime("%m"))
       .merge(df2, on="mth")
       .assign(
           p50 = lambda x: x["p50"].mul(x["pct"]),
           p90 = lambda x: x["p90"].mul(x["pct"])
       )
)