python - How can I create an argparse mutually exclusive group with multiple positional parameters? -


i'm trying parse command-line arguments such 3 possibilities below possible:

script script file1 file2 file3 … script -p pattern

thus, list of files optional. if -p pattern option specified, nothing else can on command line. said in "usage" format, this:

script [-p pattern | file [file …]]

i thought way python's argparse module this:

parser = argparse.argumentparser(prog=base) group = parser.add_mutually_exclusive_group() group.add_argument('-p', '--pattern', help="operate on files match glob pattern") group.add_argument('files', nargs="*", help="files operate on") args = parser.parse_args()

but python complains positional argument needs optional:

traceback (most recent call last):   file "script", line 92, in <module>     group.add_argument('files', nargs="*", help="files operate on") … valueerror: mutually exclusive arguments must optional

but argparse documentation says "*" argument nargs meant optional.

i haven't been able find other value nargs trick either. closest i've come using nargs="?", grabs 1 file, not optional list of number.

is possible compose kind of argument syntax using argparse?

short answer

add default * positional

long

the code raising error is, 

    if action.required:         msg = _('mutually exclusive arguments must optional')         raise valueerror(msg)

if add * parser, see required attribute set:

in [396]: a=p.add_argument('bar',nargs='*') in [397]: out[397]: _storeaction(option_strings=[], dest='bar', nargs='*', const=none, default=none, type=none, choices=none, help=none, metavar=none) in [398]: a.required out[398]: true

while ? false. i'll have dig bit further in code see why difference. bug or overlooked 'feature', or there might reason. tricky thing 'optional' positionals no-answer answer, is, empty list of values valid.

in [399]: args=p.parse_args([]) in [400]: args out[400]: namespace(bar=[], ....)

so mutually_exclusive has have way distinguish between default [] , real [].

for i'd suggest using --files, flagged argument rather positional 1 if expect argparse perform mutually exclusive testing.

the code sets required attribute of positional is:

    # mark positional arguments required if @ least 1     # required     if kwargs.get('nargs') not in [optional, zero_or_more]:         kwargs['required'] = true     if kwargs.get('nargs') == zero_or_more , 'default' not in kwargs:         kwargs['required'] = true

so solution specify default *

in [401]: p=argparse.argumentparser() in [402]: g=p.add_mutually_exclusive_group() in [403]: g.add_argument('--foo') out[403]: _storeaction(option_strings=['--foo'], dest='foo', nargs=none, const=none, default=none, type=none, choices=none, help=none, metavar=none) in [404]: g.add_argument('files',nargs='*',default=none) out[404]: _storeaction(option_strings=[], dest='files', nargs='*', const=none, default=none, type=none, choices=none, help=none, metavar=none) in [405]: p.parse_args([]) out[405]: namespace(files=[], foo=none)

the default []. parser able distinguish between default provide , 1 uses if none given.

oops - default=none wrong. passes add_argument , required test, produces mutually_exclusive error. details lie in how code distinguishes between user defined defaults , automatic ones. use none.

i don't see in documentation this. i'll have check bug/issues see topic has been discussed. it's come on before well.


Comments

Post a Comment

Popular posts from this blog

authentication - Mongodb revoke acccess to connect test database -

i have ec2 instance mongodb 3.2.0 installed. have user admin access. can connect user , perform operation remotely. 1 can connect database test remote if knows ip mongo 11.11.11.11. although not able make operations, want restrict access user credentials can connect server. first need create users , grant roles users, example: use admin db.createuser( { user: "myuseradmin", pwd: "abc123", roles: [ { role: "useradminanydatabase", db: "admin" } ] } ) then need start server --auth parameter mongod --auth more information here
Read more

r - Update two sets of radiobuttons reactively - shiny -

i have read ( how make choices in radiobuttons reactive in shiny? ) shows me how update radiobutton s in reactive way. however, when try , update 2 sets of buttons same data, 1 set renders. example: server: # create example data wafer <- rep(c(1:3), each=3) length <- c(1,1,2,1,1,1,3,5,1) width <- c(3,1,6,1,1,1,1,1,6) dd <- data.frame(wafer, length, width) shinyserver(function(input, output, session){ # create reactive dataframe store data values <- reactivevalues() values$df <- data.frame() # lengths , widths of wafer user input <- eventreactive(input$do, { subset(dd, wafer %in% input$wafer, select = length:width) }) # update reactive data frame lengths , widths have been selected user input observe({ if(!is.null(a())) { values$df <- rbind(isolate(values$df), a()) } }) output$wl <- renderdatatable({ a() }) # update radio buttons unique length , widths stored in values$df # ever "observe" put first in co...
Read more

ios - Realm over CoreData should I use NSFetchedResultController or a Dictionary? -

i'm working on app using core data , nsfetchedresultcontroller many reasons switch use realm. saw there "realm version" of nsfetchedresultcontroller on github wouldn't compatible current code using core data. the view controller displaying list of people same school, address book. list sublist of people studied in same city. so thinking make 1 unique request database retrieve list of people , filter locally list within 1 dictionary per school [string: anyobject] string section name within tableview , anyobject array of people. first solution, make nsfetchedresultcontroller each school predicate filtering location. delete actions etc.. handled delegates -> not compatible realm create dictionaries , update them each actions... -> works realm it's annoying code. any better solution? edit: i need clarify request: i'd write class inherit uitableviewcontroller. this class has list of people sorted in alphabetical order the tableview has ...
Read more