在熊猫数据框中如何应用自己的函数多个选择列并为该计算创建一个新列

Question

我的数据框（df）由 47 列和 30,000 行组成，列在下面

Index(['Unnamed: 0', 'CtpJobId', 'TransformJobStateId', 'LastError',
       'PriorityDate', 'QueuedTime', 'AccurateAsOf', 'SentToDevice',
       'StartedAtDevice', 'ProcessStart', 'LastProgressAt', 'ProcessEnd',
       'OutputFileDuration', 'Tags', 'SegmentId', 'VideoId',
       'ClipFirstFrameNumber', 'ClipLastFrameNumber', 'SourceId',
       'SourceNamedLocation', 'SourceDirectory', 'SourceFileSize',
       'srcMediaFormat', 'srcFrameRate', 'srcWidth', 'srcHeight', 'srcCodec',
       'srcDuration', 'TargetId', 'TargetNamedLocation', 'TargetDirectory',
       'TargetFilename', 'Description', 'TargetTags', 'tgtFrameRate',
       'tgtDropFrame', 'tgtWidth', 'tgtHeight', 'tgtCodec', 'DeviceType',
       'DeviceResourceId', 'AssignedDeviceId', 'DeviceName',
       'AssignedDeviceJobId', 'DeviceUri'],
      dtype='object')

我想为选择性列或该数据框应用一个函数来创建一个名为 df['seg_duration'] 的新列，所以我的函数如下

def seq_duration(df):

    if ClipFirstFrameNumber is not None and ClipLastFrameNumber is not None:
        fn = ClipLastFrameNumber -ClipFirstFrameNumber
        if FrameRate =='23.98' and DropFrame == 'False' :
            fps = 24 / 1.001
        elif FrameRate == '24' and DropFrame == 'False':
            fps = 24
        elif FrameRate == '25'and DropFrame == 'False':
            fps = 25
        elif  FrameRate == '29.97':
            fps = 30 / 1.001
        elif  FrameRate == '30' and DropFrame == 'False':
            fps = 30
        elif FrameRate == '59.94':
            fps = 60 / 1.001
        Duration = fn/fps

    elif srcDuration is not None:
         Duration = srcDuration
    else:
        None

该函数实际上有 3 种情况，在一种情况下有很多条件，所以首先我将 ClipLastFrameNumber 中的值减去 ClipFirstframeNumber 列并将其保存到 fn 变量。并应用其他逻辑，与 srcDuration 相同的是列及其值。比如下面

ClipLastFrameNumber ClipFirstFrameNumber    tgtDropFrame    tgtFrameRate
NaN                    NaN                    True          29.97
NaN                    NaN                    True          29.97
NaN                    NaN                    True          29.97
34354.0                28892.0                True          29.97

当我如下应用此功能时

df['seg_duration']=df.apply(seq_duration)

我收到错误NameError: ("name 'ClipFirstFrameNumber' is not defined", 'occurred at index Unnamed: 0')

这是为 pandas 编写函数的正确方法，或者我如何将这个函数用于该数据框并实现我的目标，即基于该函数创建一个新列 df['seg_dur']。提前致谢

Answer 1

稍微修改你的函数：

def seq_duration(row):
    Duration = None
    if row.ClipFirstFrameNumber is not None and row.ClipLastFrameNumber is not None:
        fn = row.ClipLastFrameNumber -row.ClipFirstFrameNumber
        fps = 0
        if row.FrameRate =='23.98' and row.DropFrame == 'False' :
            fps = 24 / 1.001
        elif row.FrameRate == '24' and row.DropFrame == 'False':
            fps = 24
        elif row.FrameRate == '25'and row.DropFrame == 'False':
            fps = 25
        elif  row.FrameRate == '29.97':
            fps = 30 / 1.001
        elif  row.FrameRate == '30' and row.DropFrame == 'False':
            fps = 30
        elif row.FrameRate == '59.94':
            fps = 60 / 1.001
        if fps>0:
            Duration = fn/fps

    elif row.srcDuration is not None:
         Duration = row.srcDuration

    return Duration

那么你想要：

df['seg_duration']=df.apply(seq_duration,axis = 1)