Please use R to write,

Take the county-level data and add up the total case number in each state on each day (e.g., aggregate to the state level). Store this in a data frame called `county_to_state_total_cases_df` with 3 columns:`date`, `state`, `county_total`

To avoid dplyr keeping the results "grouped" in your output, pass an additional argument to your summarize() call telling it not to keep the groups:.groups = "drop"

data set source:

https://github.com/nytimes/covid-19-data/

The county-level data set(us-counties.csv): county_df

Columns: date, county, state, fips, cases, deaths

The state-level dataset(us-states.csv): state_df

Columns: date, state, fips, cases, deaths