BUG: Incorrect parsing of ISO 8601 durations

[lmeyerov]

• [x ] I have checked that this issue has not already been reported.

• [ x] I have confirmed this bug exists on the latest version of pandas.

• (optional) I have confirmed this bug exists on the master branch of pandas.

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Code Sample, a copy-pastable example

pd.Timedelta('P1Y')
pd.Timedelta('P1M')
pd.Timedelta('P1W')
pd.Timedelta('P1D')
pd.Timedelta('P1DT1H')
pd.Timedelta('PT1H')
pd.Timedelta('P1H')

Problem description

Trying most iso8601 duration formats fails.

For above examples:

• Expected pd.Timedelta instances of 1yr, 1mo, 1wk, 1d, 1d 1hr
• ... but got ValueError: Invalid ISO 8601 Duration format - ... on Y/M/W, PT1H
• ... 1D was '0'
• ... 1DT1H was '1d' (no hr)

Encountered while trying to figure out neo4j.time.Duration().isoformat() -> pandas ->arrow > rapids cudf timedelta[*] . Neo4j returns values like P1Y3M15DT2H3M and P1Y3M.

[jreback]

Y M are not valid Timedeltas (as they are not fixed intervals)

they the other might be a bug if they are in fact ISO 8601

pull requests welcome

[lmeyerov]

This sounds like pandas docs should not say they support ISO durations

Pandas date time guide:

vs wikipedia summary of iso8601 durations:

[lmeyerov]

Linking:

#29773

#15136