pandas大家用的都很多，像我這種用的不夠熟練，也不夠多的就只能做做筆記，盡量留下點東西吧。
篩選行：
a. 按照列的條件篩選
df = pandas.DataFrame(...) # supposing it has 3 columns: a, b and c
df[(df['a'] > 0) & (df['b'] < 0) | df['c'] > 0]
b. 按照索引的條件篩選
needed_seq=[1,2,3,6]
needed_df = df.loc[needed_seq]
篩選列：
a. 篩選多列
dfs = df[['a','b']]