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I would like to use argparse to parse boolean command-line arguments written as "--foo True" or "--foo False". For example:. How can I get argparse to parse "False""F"and their lower-case variants to be False? Yet another solution using the previous suggestions, but with the "correct" parse error from argparse :. One indirectly related downside with that approach is that the 'nargs' might catch a positional argument -- see this related question and this argparse bug report.

I recommend mgilson's answer but with a mutually exclusive group so that you cannot use --feature and --no-feature at the same time. The bool always have a value assigned so that it can be used in logical statements without pre-checks.

Should one or both mean 'run the function boolor 'return a boolean'? But argparse does have registry that lets you define keywords like this. It is mostly used for actione. You can see the registered keywords with:.

There are lots of actions defined, but only one type, the default one, argparse. For the most part the programmer does not need to know about it because type and action take function and class values. There are lots of stackoverflow examples of defining custom values for both.

bool() in Python

In case it isn't obvious from the previous discussion, bool does not mean 'parse a string'. From the Python documentation:. In addition to what mgilson said, it should be noted that there's also a ArgumentParser. Not passing --my-flag evaluates to False. Do note that True values are y, yes, t, true, on and 1; false values are n, no, f, false, off and 0.

Raises ValueError if val is anything else. Learn more. Parsing boolean values with argparse Ask Question. Asked 7 years, 1 month ago. Active 6 days ago. Viewed k times.

5.4: Boolean Variables - Processing Tutorial

Peter Mortensen SuperElectric SuperElectric Here is a one-liner interpretation of mgilson's answer parser. This solution will gurantee you always get a bool type with value True or False.

This solution has a constraint: your option must have a default value. Here is a one-liner interpretation of Maxim's answer parser. When the option is used, this solution will ensure a bool type with value of True or False.

When the option is not used you will get None. Active Oldest Votes. Yet another solution using the previous suggestions, but with the "correct" parse error from argparse : def str2bool v : if isinstance v, bool : return v if v.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. The dark mode beta is finally here. Change your preferences any time.

Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I have defined a function that would print a specific string depending on its value. The parameter name is a way for the function you're defining to refer to the value it gets passed when it is called — it doesn't matter to the function how that value is spelled by the code that calls the function, and the name of the parameter doesn't matter to the calling code.

Replacing the parameter's value with a different one makes the parameter pointless — when you get to if it will be True regardless of what you passed, and myfunction "Vacation" will do the same as myfunction False. So we can simplify some more:. And further, any Python value is treated as a truth value by if.

That is, if bool e is the same as if e :. You don't need a global variable for what you're doing, but at some point, you should read Use of "global" keyword in Python to understand more about globals. This parameter is local within the function, and what you set it to only exists inside that function.

Incidentally, in your first line of the function, you set the variable to True, thereby disregarding whatever input is given.

boolean parameter python

Consequently, myfunction True and myfunction False will have the same results right now. The key point is that you pass something else when you invoke the function - either a variable or a constant term.

The first two cases simply set the first argument to True while the last one specifies the argument by name. This is perfectly valid code, but it's confusing. In that case, you have a variable local to your if clause that you use to set the argument you pass into the function, which then has a variable local to the function, of the same name. Some good reading on python scope is Short Description of the Scoping Rules? The keyword def is where you define a function.

In the second version, you're explicitly naming the argument. When you only have one argument, it's not really meaningful, so try this:. You can then do foowhich will print "8 hello True". Or you can do foo 7which will explicitly set arg1 and use the defaults for arg2 and arg3, and print "7 hello True". Or foo 6, 'goodbye' prints "6 goodbye True", or foo 5, 'whatever', Falsewill print "5 whatever False".

But how can you use defaults and only change the last argument? That's where named parameters come in.

boolean parameter python

The best way to learn is by doing. Experiment with small functions like this one, inside the python interpreter. You'll get the hang of it quickly.

Learn more. How to define a boolean parameter in Python Ask Question. Asked 1 year, 6 months ago. Active 1 year, 6 months ago.

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Viewed 4k times.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information.

Basically I want to pass a flag into my script which will tell the script whether to do a specific action or not. Learn more. Boolean argument for script Ask Question. Asked 8 years, 2 months ago. Active 2 years, 7 months ago. Viewed 49k times. In Python, I understand how int and str arguments can be added to scripts.

Brad Koch What behavior do you want with booleans? Active Oldest Votes. PaulDraper: Explicit is better than implicit.

PaulDraper I've checked that it isn't needed, but you can put it as an explicit value.

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PaulDraper Isn't the default for boolean True? Ned Batchelder Ned Batchelder k 64 64 gold badges silver badges bronze badges. ThorSummoner ThorSummoner 9, 8 8 gold badges 88 88 silver badges bronze badges. Sign up or log in Sign up using Google.

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It only takes a minute to sign up. I have a script tool which requires a parameter folder path to a gdB, via GetParameterAsText so that a later process can be saved there. The thing I want to do is make an Optional Boolean parameter, that when checked, automatically fills in the folder path gdB parameter.

The boolean text asks the user, "Use default workspace? I have already created the boolean parameter in the script tool, I am however unaware of how to "fill in" the required parameter based on the user's boolean.

I have a suspicion without testing that it may be returning 'True' or 'False' rather than 'true' or 'false'. Also, arcpy. If you use arcpy. GetParameter then you will be able to test for the Booleans True or False.

Extending PolyGeo's answer, running this snippet from the command line and from a toolbox with a single parameter set as "boolean, optional" will give slightly different returns. So the useDefault parameter is not a native python boolean.

You sadly can't use standard python idioms like if useDefault Strictly speaking the. It's added here for clarity and flexibility. You can, however, try:. Sign up to join this community. The best answers are voted up and rise to the top. Home Questions Tags Users Unanswered. Ask Question. Asked 4 years, 9 months ago. Active 8 days ago. Viewed 6k times. Active Oldest Votes. Try adding a print useDefault immediately after you set it to see what is returned.

GetParameterAsText 0 report to Arcgis message queue arcpy.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. But, please let me know if there is any other effective or better way to pass boolean values as input to another method?

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If what you mean is how to pass specific parameters but not others, Python has "keyword parameters":. Learn more.

boolean parameter python

Pass boolean values as input to method Ask Question. Asked 3 years, 3 months ago. Active 3 years, 3 months ago. Viewed 34k times. How do I pass boolean as argument to a method?

Arun Shankar. Arun Shankar Arun Shankar 1 1 gold badge 14 14 silver badges 29 29 bronze badges. If you don't pass it, False will be the default value passed. Same way you pass any other parameter.

Booleans aren't special. Why do you make it a string? Active Oldest Votes.

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There's nothing special about True or False values Thank you, but what if the value for c is coming from other method and the variable name is x? Can't see the problem here. Boolean is a data type and can be passed around as any other data type.

boolean parameter python

Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. The Overflow Blog. Socializing with co-workers while social distancing.The bool method is used to return or convert a value to a Boolean value i. The bool method in general takes only one parameter here xon which the standard truth testing procedure can be applied.

If no parameter is passed, then by default it returns False. So, passing a parameter is optional. It can return one of the two values. Except these all other values return True.

Booleans, True or False in Python

Here is a program to find out even and odd by the use of bool method. You may use other inputs and check out the results. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below. Writing code in comment?

Please use ide. Syntax: bool [x] The bool method in general takes only one parameter here xon which the standard truth testing procedure can be applied.

It returns True if the parameter or value passed is True. It returns False if the parameter or value passed is False. Python program to illustrate.

Returns False as x is not equal to y. Returns False as x is an empty sequence. Returns False as x is an emty mapping. Returns True as x is a non empty string. Python code to check whether a number. Chinmoy Lenka.

Check out this Author's contributed articles. Load Comments.Booleans represent one of two values: True or False. In programming you often need to know if an expression is True or False.

You can evaluate any expression in Python, and get one of two answers, True or False. When you compare two values, the expression is evaluated and Python returns the Boolean answer:.

When you run a condition in an if statement, Python returns True or False :. Print a message based on whether the condition is True or False :.

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The bool function allows you to evaluate any value, and give you True or False in return. Almost any value is evaluated to True if it has some sort of content.

Any number is Trueexcept 0. Any list, tuple, set, and dictionary are Trueexcept empty ones. And of course the value False evaluates to False. Python also has many built-in functions that returns a boolean value, like the isinstance function, which can be used to determine if an object is of a certain data type:. If you want to report an error, or if you want to make a suggestion, do not hesitate to send us an e-mail:. Example Evaluate a string and a number: print bool "Hello" print bool Example The following will return True: bool "abc" bool bool ["apple", "cherry", "banana"].

Example Print "YES!

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Exercise: The statement below would print a Boolean value, which one? HOW TO. Your message has been sent to W3Schools. W3Schools is optimized for learning, testing, and training. Examples might be simplified to improve reading and basic understanding.

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