Clean_and_sort_df.jl

# Create an independent copy
df_pedometer = deepcopy(df_pedometer_raw)

# Set format for the DateTime object
datef = dateformat"y-m-d H:M:S.s"

# Convert create_time column from string into DateTime objects
df_pedometer[!, :create_time] = DateTime.(df_pedometer_raw[!, :create_time], datef)

# Convert distance into km and time into minutes
df_pedometer[!, :distance] = df_pedometer_raw[!, :distance]/1000  # to km
df_pedometer[!, :active_time] = df_pedometer[!, :active_time]/60000 # to minutes

# Remove rows which have type 'missing' in the source_info column, this gets rid of duplicates. 
# @dropna macro comes from Query.jl
df_pedometer = df_pedometer |> @dropna(:source_info) |> DataFrame

# Sort the DataFrame in the order of increasing time
sort!(df_pedometer, :create_time)