df['tag'] = df['Value'] < 1.0
df['mask'] = np.where(df['tag'],1,0)
first = df.index[df['tag'] & ~ df['tag'].shift(1).fillna(False)]
last = df.index[df['tag'] & ~ df['tag'].shift(-1).fillna(False)]
pr = [(i, j) for i, j in zip(first, last) if j > i + 1]

df[:tag]=df[:Value] .< 1.0
df[:mask]=zeros(length(df[:tag]))

df[:mask][df[:tag].==true] .= 1
df[:mask][df[:tag].==false] .= 0