otp.Operation.map#

Operation.map(arg, default=None)#

Map values of the column to new values according to the mapping in arg. If the value is not in the mapping, it is set to the default value. If default value is not set, it is set to default value for the column type.

Parameters

  • arg (dict) – Mapping from old values to new values. All values must have the same type, compatible with the column type.

  • default (simple value or Column or Operation) – Default value if no mapping is found in arg. By default, it is set to default value for the column type. (0 for numbers, empty string for strings, etc.)

Return type

Operation

Examples

>>> t = otp.Ticks(A=[1, 2, 3, 4, 5])
>>> t['B'] = t['A'].map({1: 10, 2: 20, 3: 30})
>>> otp.run(t)
                     Time  A   B
0 2003-12-01 00:00:00.000  1  10
1 2003-12-01 00:00:00.001  2  20
2 2003-12-01 00:00:00.002  3  30
3 2003-12-01 00:00:00.003  4   0
4 2003-12-01 00:00:00.004  5   0

Example with default parameter set:

>>> t = otp.Ticks(A=[1, 2, 3, 4, 5])
>>> t['B'] = t['A'].map({1: 10, 2: 20, 3: 30}, default=-1)
>>> otp.run(t)
                     Time  A   B
0 2003-12-01 00:00:00.000  1  10
1 2003-12-01 00:00:00.001  2  20
2 2003-12-01 00:00:00.002  3  30
3 2003-12-01 00:00:00.003  4  -1
4 2003-12-01 00:00:00.004  5  -1

default parameter can also be an Operation or Column. For example, to keep unmapped values:

>>> t = otp.Ticks(A=[1, 2, 3, 4, 5])
>>> t['B'] = t['A'].map({1: 10, 2: 20, 3: 30}, default=t['A'])
>>> otp.run(t)
                     Time  A   B
0 2003-12-01 00:00:00.000  1  10
1 2003-12-01 00:00:00.001  2  20
2 2003-12-01 00:00:00.002  3  30
3 2003-12-01 00:00:00.003  4   4
4 2003-12-01 00:00:00.004  5   5