string-formatting

问题 How can I use variables to format my variables? cart = {"pinapple": 1, "towel": 4, "lube": 1} column_width = max(len(item) for item in items) for item, qty in cart.items(): print "{:column_width}: {}".format(item, qty) > ValueError: Invalid conversion specification or (...): print "{:"+str(column_width)+"}: {}".format(item, qty) > ValueError: Single '}' encountered in format string What I can do, though, is first construct the formatting string and then format it: (...): formatter = "{:"+str

问题 I have some decimal data coming from an external service. I need to format the data to 2 decimal places as it is represents money, but if I use the standard C format, I rounds the number: var x = 42.999m; var y = string.Format("{0:C}", x); This results in y containing £43.00. How can I have it round down to £42.99? (Note that this question is not the same) 回答1: If you want to use a non-default rounding strategy, you'd need to do something like: var x = 42.999m; var y = string.Format("{0:C}",

问题 Currently have code that looks something like; print '{: <5}'.format('test') This will pad my string with ' ' if it is less than 5 characters. If the string is more than 5 characters, I'd need the string to be truncated. Without explicitly checking the length of my string before formatting it, is there a better way to pad if less than fixed length or truncate if greater than fixed length? 回答1: You can use 5.5 to combine truncating and padding so that the output will always be of length of

问题 Given a string of unknown length, how can you output it using cout so that the entire string displays as an indented block of text on the console? (so that even if the string wraps to a new line, the second line would have the same level of indentation) Example: cout << "This is a short string that isn't indented." << endl; cout << /* Indenting Magic */ << "This is a very long string that will wrap to the next line because it is a very long string that will wrap to the next line..." << endl;

问题 Given a string of unknown length, how can you output it using cout so that the entire string displays as an indented block of text on the console? (so that even if the string wraps to a new line, the second line would have the same level of indentation) Example: cout << "This is a short string that isn't indented." << endl; cout << /* Indenting Magic */ << "This is a very long string that will wrap to the next line because it is a very long string that will wrap to the next line..." << endl;

问题 I have a program which deals with nested data structures where the underlying type usually ends up being a decimal. e.g. x={'a':[1.05600000001,2.34581736481,[1.1111111112,9.999990111111]],...} Is there a simple pythonic way to print such a variable but rounding all floats to (say) 3dp and not assuming a particular configuration of lists and dictionaries? e.g. {'a':[1.056,2.346,[1.111,10.000],...} I'm thinking something like pformat(x,round=3) or maybe pformat(x,conversions={'float':lambda x:

问题 I am using python's log formatter to format log records and i have a fmt value of fmt = "[%(filename)s:%(lineno)s] %(message)s" What i would like is that "[file.py:20]" to be stretched to 10 characters wide (for example). If it was one value that would have been easy but is there any way to stretch this entire structure to a specified length? I want something like: tmp = "[%(filename)s:%(lineno)s]" fmt = "%(tmp)10s %(message)s" I would like to know if this is possible using string formatting

问题 I am using python's log formatter to format log records and i have a fmt value of fmt = "[%(filename)s:%(lineno)s] %(message)s" What i would like is that "[file.py:20]" to be stretched to 10 characters wide (for example). If it was one value that would have been easy but is there any way to stretch this entire structure to a specified length? I want something like: tmp = "[%(filename)s:%(lineno)s]" fmt = "%(tmp)10s %(message)s" I would like to know if this is possible using string formatting

问题 I am using webservice in my android application. In my webservice result I get a HTML formatted String as result. Assume this is my web service result: Books on Chennai :\n Madras Discovered, Tales of Old and New Madras, Madras (1992) by S. Muthiah \n Madras – its Past and its Present (1995) by S. Muthiah \n Madras – its Yesterdays and Todays and Tomorrows by S. Muthiah \n At Home in Madras (1989) by S. Muthiah \n The Spirit of Chepauk (1998) by S. Muthiah \n The Story Of Fort St. George

问题 When formatting a string, my string may contain a modulo "%" that I do not wish to have converted. I can escape the string and change each "%" to "%%" as a workaround. e.g., 'Day old bread, 50%% sale %s' % 'today!' output: 'Day old bread, 50% sale today' But are there any alternatives to escaping? I was hoping that using a dict would make it so Python would ignore any non-keyword conversions. e.g., 'Day old bread, 50% sale %(when)s' % {'when': 'today'} but Python still sees the first modulo %