Visidata: Not able to use python expression

[aborruso]

Hi,
I have loaded datetime module and I have a column with dates. The name of this field is "data".
If I use this expression expr=datetime.strptime(data, '%Y-%m-%d').month I have no value.

Ho to reference the field "data" in the expression??

Thank you

[saulpw]

Hi @aborruso, use the = command and then type the datetime.strptime... expression. Don't put expr at the beginning.

[aborruso]

Hi @saulpw

Hi @aborruso, use the = command and then type the datetime.strptime... expression. Don't put expr at the beginning.

I know but I have

If I use a fixed value it works

Thank you

[zakora]

Hi,

I think the error is that you are using the datetime module but visidata doesn't provide it as is when writting python expression.

What you can do instead:

• mark the data as date with @, as you did
• you can now use the data column directly as datetime objects, so you can start an expr with =, then write data.month.

[aborruso]

Hi @zakora ,
I can use datetime moduke because I have inserted it in .visidatarc file. And for this reason datetime.strptime("2018-08-08", '%Y-%m-%d').month works.
Than it should work also using some existing field.

But your great tip to use simply data.month, after applying @ gives me the answer.

I applied datetime.strptime to a field that was already datetime. Then I had to apply "~" to the field and it works great!

Thank you

My .visidatarc

options.color_key_col=''
options.color_selected_row='yellow'
options.color_note_type='yellow'
options.color_graph_hidden='blue'
options.color_column_sep='blue'

from datetime import datetime

[saulpw]

@aborruso Also, when you see an error in a cell like that (with the ! as the note), you can press z Ctrl+E (with the cursor over the error cell) to see the error as a Python stacktrace, which might help you diagnose the issue.