Invalid syntax with an f-string

Invalid syntax with an f-string - Printable Version

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Invalid syntax with an f-string - Mark17 - Jan-13-2022

I'm getting invalid syntax with Python showing a carrot under the first colon. What did I do wrong?

                    print({}, ",", {}, ",", {}, ",", {}, ",", {}, ",", {}, ",", {:.2f}, ",", {:.2f}, ",", {:.2f}, ",", {}, ",",
                        {:.2f}, ",", {}, ",", {}, ",", {}, ",", {}, ",", {}, ",", {:.2f}, ",", {:.2f}, ",", {}, ",", {:.2f},
                        ",", {:.2f}, ",", {:.2f}, ",", {:.2f}.format(spread_count, date, trade_date, L_spx, L_strike, L_price,
                        L_iv, L_delta, L_theta, S_price, S_iv, L_exp_mo, L_dte_trade_inception, S_exp_mo, S_dte_trade_inception,
                        spread_width, S_delta, S_theta, P_price, P_delta, P_theta, P_t_d, P_skew), file=strike_file) #testing f-string formatting

RE: Invalid syntax with an f-string - deanhystad - Jan-13-2022

That is not f-string formatting, that is the format() command and it is really, really wrong.

f-string looks like this:

count = 1
price = 1.2
name = "My name"
print(f"{count}, {name}, {price:.2f}")

RE: Invalid syntax with an f-string - Mark17 - Jan-13-2022

(Jan-13-2022, 11:10 PM)deanhystad Wrote: That is not f-string formatting, that is the format() command and it is really, really wrong.

f-string looks like this:
count = 1
price = 1.2
name = "My name"
print(f"{count}, {name}, {price:.2f}")

My mistake... I had that confused.

In any case, what's wrong with the syntax in my usage of the format command here? Note: the output is to a .csv file with over 20 columns, which is why I have all the ",", and such.

RE: Invalid syntax with an f-string - snippsat - Jan-14-2022

(Jan-13-2022, 11:41 PM)Mark17 Wrote: In any case, what's wrong with the syntax in my usage of the format command here?

Almost all of it is wrong,learn to test smaller part before writing so much.

To give some example how it can be done

import csv

with open('birthday.csv') as csv_file:
    reader = csv.reader(csv_file, delimiter=',')
    for row in reader:
        print('{:<15}  {:<15}  {:<15}'.format(*row))

Output:name             department       birthday month 
John Smith       Accounting       November       
Erica Meyers     IT               March

Pandas and tabulate

from tabulate import tabulate
import pandas as pd

df = pd.read_csv('birthday.csv')
print(tabulate(df, headers='keys', tablefmt='psql', showindex=False))

Output:+--------------+--------------+------------------+
| name         | department   | birthday month   |
|--------------+--------------+------------------|
| John Smith   | Accounting   | November         |
| Erica Meyers | IT           | March            |
+--------------+--------------+------------------+

CSV file used:

Output:name,department,birthday month
John Smith,Accounting,November
Erica Meyers,IT,March

RE: Invalid syntax with an f-string - BashBedlam - Jan-14-2022

It looks like this is what you're looking for:

spread_count = 27.24583
date = 'Jan 13 2022'
trade_date = 'yesterday'
L_spx = 144
L_strike = 'None'
print ('{0:.2f},{1},{2},{3}'.format(spread_count, date, trade_date, L_spx, L_strike))

Output:
27.25,Jan 13 2022,yesterday,144

RE: Invalid syntax with an f-string - Mark17 - Jan-14-2022

(Jan-14-2022, 02:15 AM)BashBedlam Wrote: It looks like this is what you're looking for:

spread_count = 27.24583
date = 'Jan 13 2022'
trade_date = 'yesterday'
L_spx = 144
L_strike = 'None'
print ('{0:.2f},{1},{2},{3}'.format(spread_count, date, trade_date, L_spx, L_strike))

Output:
27.25,Jan 13 2022,yesterday,144

Nice... looks like it works without the numbers too and I don't need all those extra commas in quotes to get the values into separate cells. Thanks!

RE: Invalid syntax with an f-string - snippsat - Jan-14-2022

With f-string that preferable and modern way to use now,it would be like.

spread_count = 27.24583
date = 'Jan 13 2022'
trade_date = 'yesterday'
L_spx = 144
L_strike = 'None'
print (f'{spread_count:.2f},{date},{trade_date},{L_strike}')

Output:
27.25,Jan 13 2022,yesterday,None

Python 3's f-Strings: An Improved String Formatting Syntax (Guide)

RE: Invalid syntax with an f-string - Mark17 - Jan-14-2022

(Jan-14-2022, 03:37 PM)snippsat Wrote: With f-string that preferable and modern way to use now,it would be like.
spread_count = 27.24583
date = 'Jan 13 2022'
trade_date = 'yesterday'
L_spx = 144
L_strike = 'None'
print (f'{spread_count:.2f},{date},{trade_date},{L_strike}')
Output:
27.25,Jan 13 2022,yesterday,None
Python 3's f-Strings: An Improved String Formatting Syntax (Guide)

I'll try to start using f-strings and getting used to this. Thanks!