Sharing a script: solve arbitrary blocks of text as math.

paultopia

A common task I have: I want to write down some numbers or a simple formula of some kind, and then go ahead and do something with the numbers or solve a simple equation with them. Examples: writing down how much I paid for each bill in a note or drafts, then summing them; working out a simple algebra equation for something like a mildly complicated tax/tip situation and then solving it.

There are lots of calculators in the built-in Pythonista examples, but none which quite met my needs for dealing with pre-written text. There are also special-purpose apps for things like ticker-tape calculators, but I don't think any of them do algebra, and, besides, why pay for a separate app when pythonista is right there plus has the full power of sympy available?

So I wrote my own little script. Takes share sheet or clipboard input string. If it's just a list of numbers, sums them. If there are arithmetic operators, evaluates the expression. If it's a simple one-variable expression, assumes it's an equation with the other side zero and feeds it to sympy to solve. If it's a one-variable equation, back to sympy. Should handle most basic day-to-day ticker-tape math needs, in only 75-ish lines of actual code.

https://gist.github.com/paultopia/16e69f9f72ad0a5000fa5b4575ddeee2

cvp

@mikael said:

I made an Apple shortcut to enter the text

Why do you want to enter the numbers in a shortcut and not in Pythonista which could allow a user keyboard with only digits?

mikael

@cvp, actually started from the dictation, then when that was initially quite unreliable, checked out what the typing experience was like.

After checking the out of the box capabilities, I am now moving full hog to Pythonista.

First thing I noted was that iOS is really missing a native keyboard option that would be spot on for a calculator.

cvp

@mikael easy with this

mikael

@cvp, very true. Would need to add a few mathematical operations, and then it would be perfect. Does the user have to give permission if you use this?

mikael

@paultopia, to make sure I understand what is happening, and to add a few features like result precision and tokenization, I re-implemented your code as a class. It is here, intended to be used like this:

    >>> Kalkylation("1 2\\n3")
    Input: 1 + 2 + 3
    Symbolic result: 6
    Numeric result: 6.00
    
    >>> k = Kalkylation("1 = 2+x")
    >>> k
    Input: 1 = 2 + x
    Symbolic result: -1
    Numeric result: -1.00
    
    >>> k.tokens
    ['1', '=', '2', '+', 'x']
    
    >>> Kalkylation.result_decimals = '.000001'
    
    >>> Kalkylation("1+23 =3+x**2")
    Input: 1 + 23 = 3 + x ** 2
    Symbolic result: -sqrt(21), sqrt(21)
    Numeric result: -4.582576, 4.582576

cvp

@mikael said:

Does the user have to give permission if you use this?

Sorry if I don't understand your question but my code is available here

mikael

@cvp, I meant that this looks like an in-app keyboard, which is excellent, as cross-app custom keyboards need to ask for permission.

cvp

@mikael ok, sorry, in-app

cvp

@mikael error

NameError: name 'ROUND_HALF_EVEN' is not defined

from decimal import Decimal, ROUND_HALF_EVEN

mikael

@cvp, curious, works for me. Restart Pythonista?

cvp

@mikael As this is a "from decimal", it seems normal to import it, isn't it?

from decimal import Decimal, ROUND_HALF_EVEN

Has solved

cvp

Copy my SetTextFieldPad from GitHub and place this code after @mikael 's module


import ui
from SetTextFieldPad import SetTextFieldPad

def my_action(sender):
    sender.TextField.close()

 
tf = ui.TextField()
#pad = [{'key':'','title'=:'','icon':''}]
pad = [{'key':'1'},{'key':'2'},{'key':'3'},
        {'key':'back space','icon':'typb:Delete'},
        {'key':'new row'},
        {'key':'4'},{'key':'5'},{'key':'6'},
        {'key':'delete','icon':'emj:Multiplication_X'},
        {'key':'new row'},
        {'key':'7'},{'key':'8'},{'key':'9'},
        {'key':'x'},
        {'key':'new row'},
        {'key':'+'},{'key':'='},
        {'key':'⏎', 'action':my_action},
        {'key':'new row'},
        {'key':'nul'},{'key':'0'}]
SetTextFieldPad(tf,pad=pad)
tf.text = ''
tf.width = 400
tf.present('sheet')
tf.begin_editing()
tf.wait_modal()
k = Kalkylation(tf.text)
print(k)

And you will get

mikael

@cvp said:

from decimal import Decimal, ROUND_HALF_EVEN

My turn to misunderstand, sorry. I thought you had already added this, and it still wasn’t finding it.

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