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pythonpandas
Lazerhorse
Lazerhorse

Reputation: 123

Counter while using Pandas dataframe (Python)

I want update the column counter to counter + 1 every time in encounters the string [hr]. My column named "Counter" would ideally look like 11111,22222,33333 .... 999999 s=

This is

My code is below

df['Counter'] = df['elapsed time'].apply(lambda x: 1 if x != "[hr]" else 2)

I try with the below but get the error SyntaxError: lambda cannot contain assignment

Is there a way around this?

df['Counter'] = df['elapsed time'].apply(lambda x: 1 if x != "[hr]" else x =+ 1)

Example dataframe

      elapsed time distance travelled significant wave height  total  Counter
0             [hr]               [nm]                            [m]        2
1            0.000              0.000                          1.035        1
2            3.000              0.000                          0.000        1
3            6.000              0.000                          0.000        1
4            9.000              0.000                          0.000        1
...            ...                ...                            ...      ...
76774      320.638           4181.591                          0.000        1
76775      321.000           4186.698                          0.000        1
76776      322.116           4202.445                          0.000        1
76777      323.181           4217.467                          0.000        1

Upvotes: 1

Views: 121

Answers (1)

jezrael
jezrael

Reputation: 863031

If want count next values after [hr] value then compare values forst and then use cumulative sum:

df['Counter'] = df['elapsed time'].eq("[hr]").cumsum()

Upvotes: 1

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