panda用数据帧值作为字符串填充列表

Question

我正在从文件夹中读取csv文件，并将tem过滤到pandas数据帧中，如下所示：

results=[]
for filename in glob.glob(os.path.join('/path/*.csv')):
  with open(filename) as p:
    df = pd.read_csv(p)

    filtered = df[(df['duration'] > low1) & (df['duration'] < high1)]

    artist = filtered['artist'].values
    print artist
    track = filtered['track'].values
    print track

其中low1 = 0，high_1 = 0.5

artist和track将数百个过滤后的项目作为普通字符串打印出来，但是如果我尝试将它们附加到循环中的results中：

^{pr2}$

{I>和填充了

如何用常规的results填充results，以这种方式：

[['artist1', 'track1'], ['artist1', 'track2], ...]]

Answer 1

创建DataFrame的列表，然后通过^{}将它们连接在一起，最后转换为嵌套列表：

results=[]
for filename in glob.glob(os.path.join('/path/*.csv')):
    df = pd.read_csv(filename)
    #filter by conditions and also columns by names with .loc
    filtered = df.loc[(df['duration'] > low1) & (df['duration'] < high1), ['artist','track']]
    #alternative solution 
    filtered = df.loc[df['duration'].between(low1, high1,inclusive=False), ['artist','track']]
    results.append(filtered) 

out = pd.concat(results).values.tolist()

另一个解决方案id追加列表，最后通过列表理解将其展平：

^{pr2}$