R subset filterout specific dates from vector

Question

Hello i have big problem with R I have data like this:

df:

Dates        unique ID
20180101     10
20180101     20
20180101     18
20180201     34
20180101     10
...
20180330     10

I have about 1kk rows with unique id of specific client login. Its around 600 rows a day . But i want to filterout or subset only specific dates.

so i have created

id_list = c(20180101,20180102)

Then i have tried to subset:

 df = subset(df,df$Dates == id_list)

But my new df has missing values like each 2nd one is missing. I know in this exapple i can do

df = subset(df,df$Dates == 20180101|20180330)

I want to do this with bigger list of about 50 dates in id_list.