understanding the insert method in Tkinter's Entry widget - python

I've been going through a tutorial on Python's Tkinter, I'm currently working with the Entry widget and just came across the insert method. I understand what the method does (makes a default string to appear in a text entry field), but what I don't get is the method's first parameter, which to the best of my understanding is the index at which the string should start. now here comes the confusion. When playing around with it, giving different values for the index parameter, every time I run it the text appears in the same spot (at the very beginning). So as best I can tell, I'm either doing something wrong or, I'm misunderstanding the documentation. this is a snippet from my code:
e1 = Entry(master)
e1.insert(0,"First Name")
When ever I run this, weather the index is 0, 10 or 100 the text "First Name" always appears at the very beginning of the text field


First, the statement "makes a default string appear" is not quite true. While it can be used to insert default text, it more correctly is described simply as inserting text, period. It can be default text, replacement text, additional text, whatever you want.
Any index that is before the first character is treated as 0 (zero). Any index that is after the last character is treated as being the end. When you insert something into an entry widget that is empty, every index is treated as 0. Thus, the index is mostly useful for inserting text somewhere into existing text.
For example:
e1 = Entry(master)
e1.insert(0, "hello")
e1.insert("end", "world")
e1.insert(5, ", ")
As an application programmer, you will almost never use the insert method with anything other than an index of 0 (zero) or "end", and perhaps "insert". However, when you try to add advanced functionality (eg: spell checking, auto-complete, etc) you will find the index to be highly useful.


In this line:
text.insert('1.0', 'here is my\ntext to insert')
The "1.0" here is the position where to insert the text, and can be read as "line 1, character 0". This refers to the first character of the first line. Historically, especially on Unix, programmers tend to think about line numbers as 1-based and character positions as 0-based.
The text to insert is just a string. Because the widget can hold multi-line text, the string we supply can be multi-line as well. To do this, simply embed \n (newline) characters in the string at the appropriate locations.
From the Tk docs https://tkdocs.com/tutorial/text.html


you use it when you use multiple insert() method
for example:
e = Entery(window)
e.pack()
e.insert(0, "Hi")
e.insert(2, " there")
Note : in " there" you should have a space behind it or else it will appear like this (Hithere)

Related

Tkinter text integer to text index

Is there a way to get way to get an integer to a valid Tkinter text widget position. For example, 0 would get changed to '1.0' and if there were no characters on line 1, 1 would go to '2.0'. I am aware of the widget's index method however only to get the cursor position (in case this is the answer).
Many thanks
EDIT
I believe (having now done more research on the matter) that the Tk Text widget lazy loads the text (for performance). Therefore, without you getting the entire text contents and performing string actions on that, I don't think its possible (the Tk Text only has a minor understanding of what is above and below the currently viewed text - hence why a horizontal scrollbar will constantly adjust when scrolling vertically).

The text widget supports many modifiers to an index. For example, you can take an existing index and compute a new index by adding or subtracting characters or lines. For example, if you want to get the first 10 characters on line 2 you can use "2.0 + 10 chars" (or the more compact "2.0+10c"). If you want the 100th character in the text widget you can use "1.0+100c", etc.
In addition to characters, you can add or subtract lines (eg: "end-1line"), and you can get the start or end of a word or line (eg: "end-1c linestart" represents the first character of the last line in the widget).
You can read about all of the forms an index can take in the canonical tcl/tk documentation: http://tcl.tk/man/tcl8.5/TkCmd/text.htm#M7

Numerical keyboard Python

I am recording responses during a simple calculation task in Python, and I am storing these in a string. I would like to use the numerical part of the keyboard, but these give for instance 'num_1' instead of '1'. It probably has something to do that I store the input as a Text Stimulus in PsychoPy.. Any way to get around this?
CapturedResponseString = visual.TextStim(myWin,
units='norm',height = 0.2,
pos=(0,-0.40), text='',
alignHoriz = 'center',alignVert='center', color=[-1,-1,-1])
captured_string = '' #key presses will be captured in this string

If all your responses are preceded by "num_" you can just amputate them. For example int(CapturedResponseString[4:]) will grab the numerical portion and turn it into an integer.
Python has lots of string processing tools that are much more sophisticated than this, and they are all available to you when using Psychopy. For example you could also split at the underscore. CapturedResponseString.split('_') will return a list with the stuff before the underscore in the first position and the rest in the second (assuming only one underscore).

Type Error: get() takes at least 2 arguments, 1 given

I am trying to create a statement which checks whether a TextBox is empty, if that is not the case and the TextBox is not empty, then I want the textBox to refresh itself.
I have tried the following:
if (len(self.txtBox.get() != 0)):
self.txtBox.update()
print "Textbox was not empty"
However I am given the following error, 'Type Error: get() takes at least 2 arguments, 1 given '. I know the error indicates that I should pass an argument in the get function, however I have seen code snippets using the get() function without passing any arguments, and either way I do not know what argument I should pass.
Any help would be greatly appreciated.

There is no widget called a "TextBox", so I don't know if you're talking about an Entry widget or a Text widget. The get method of the entry widget can be called without parameters, but the get method of the text widget requires two parameters. The two parameters are the starting and ending points of a region.
To get everything in a text widget, you should do it like this:
self.txtBox.get("1.0", "end-1c")
The "1.0" represents the first character, and "end-1c" represents the last character ("end") minus one character ("-1c") which will ignore the trailing newline that is always added by tkinter itself.

This old message from the python-tutor list might help. The two parameters are bizarre (to my mind: I am not a Tk expert) pointers, similar to string slicing but with the "pointers" being decimal numbers where the integer portion specifies the line and the decimal places specify the character numbers.

Returning position where a label wraps text (tkinter)

I was wondering if it was possible to return the position or character where a label wraps text, as I would like to append a "\n" into the string being printed in the label after said character. Believe it or not, I do have a good reason for doing this, although it is somewhat complicated to explain.

Invalid character in identifier

I am working on the letter distribution problem from HP code wars 2012. I keep getting an error message that says "invalid character in identifier". What does this mean and how can it be fixed?
Here is the page with the information.
import string
def text_analyzer(text):
'''The text to be parsed and
the number of occurrences of the letters given back
be. Punctuation marks, and I ignore the EOF
simple. The function is thus very limited.
'''
result = {}
# Processing
for a in string.ascii_lowercase:
result [a] = text.lower (). count (a)
return result
def analysis_result (results):
# I look at the data
keys = analysis.keys ()
values \u200b\u200b= list(analysis.values \u200b\u200b())
values.sort (reverse = True )
# I turn to the dictionary and
# Must avoid that letters will be overwritten
w2 = {}
list = []
for key in keys:
item = w2.get (results [key], 0 )
if item = = 0 :
w2 [analysis results [key]] = [key]
else :
item.append (key)
w2 [analysis results [key]] = item
# We get the keys
keys = list (w2.keys ())
keys.sort (reverse = True )
for key in keys:
list = w2 [key]
liste.sort ()
for a in list:
print (a.upper (), "*" * key)
text = """I have a dream that one day this nation will rise up and live out the true
meaning of its creed: "We hold these truths to be self-evident, that all men
are created equal. "I have a dream that my four little children will one day
live in a nation where they will not be Judged by the color of their skin but
by the content of their character.
# # # """
analysis result = text_analyzer (text)
analysis_results (results)

The error SyntaxError: invalid character in identifier means you have some character in the middle of a variable name, function, etc. that's not a letter, number, or underscore. The actual error message will look something like this:
File "invalchar.py", line 23
values = list(analysis.values ())
^
SyntaxError: invalid character in identifier
That tells you what the actual problem is, so you don't have to guess "where do I have an invalid character"? Well, if you look at that line, you've got a bunch of non-printing garbage characters in there. Take them out, and you'll get past this.
If you want to know what the actual garbage characters are, I copied the offending line from your code and pasted it into a string in a Python interpreter:
>>> s=' values ​​= list(analysis.values ​​())'
>>> s
' values \u200b\u200b= list(analysis.values \u200b\u200b())'
So, that's \u200b, or ZERO WIDTH SPACE. That explains why you can't see it on the page. Most commonly, you get these because you've copied some formatted (not plain-text) code off a site like StackOverflow or a wiki, or out of a PDF file.
If your editor doesn't give you a way to find and fix those characters, just delete and retype the line.
Of course you've also got at least two IndentationErrors from not indenting things, at least one more SyntaxError from stay spaces (like = = instead of ==) or underscores turned into spaces (like analysis results instead of analysis_results).
The question is, how did you get your code into this state? If you're using something like Microsoft Word as a code editor, that's your problem. Use a text editor. If not… well, whatever the root problem is that caused you to end up with these garbage characters, broken indentation, and extra spaces, fix that, before you try to fix your code.

If your keyboard is set to English US (International) rather than English US the double quotation marks don't work. This is why the single quotation marks worked in your case.

Similar to the previous answers, the problem is some character (possibly invisible) that the Python interpreter doesn't recognize. Because this is often due to copy-pasting code, re-typing the line is one option.
But if you don't want to re-type the line, you can paste your code into this tool or something similar (Google "show unicode characters online"), and it will reveal any non-standard characters. For example,
s=' values ​​= list(analysis.values ​​())'
becomes
s=' values U+200B U+200B​​ = list(analysis.values U+200B U+200B ​​())'
You can then delete the non-standard characters from the string.

Carefully see your quotation, is this correct or incorrect! Sometime double quotation doesn’t work properly, it's depend on your keyboard layout.

I got a similar issue. My solution was to change minus character from:
—
to
-

I got that error, when sometimes I type in Chinese language.
When it comes to punctuation marks, you do not notice that you are actually typing the Chinese version, instead of the English version.
The interpreter will give you an error message, but for human eyes, it is hard to notice the difference.
For example, "，" in Chinese; and "," in English.
So be careful with your language setting.

Not sure this is right on but when i copied some code form a paper on using pgmpy and pasted it into the editor under Spyder, i kept getting the "invalid character in identifier" error though it didn't look bad to me. The particular line was grade_cpd = TabularCPD(variable='G',\
For no good reason I replaced the ' with " throughout the code and it worked. Not sure why but it did work

A little bit late but I got the same error and I realized that it was because I copied some code from a PDF. Check the difference between these two:
-
−
The first one is from hitting the minus sign on keyboard and the second is from a latex generated PDF.

This error occurs mainly when copy-pasting the code. Try editing/replacing minus(-), bracket({) symbols.

You don't get a good error message in IDLE if you just Run the module. Try typing an import command from within IDLE shell, and you'll get a much more informative error message. I had the same error and that made all the difference.
(And yes, I'd copied the code from an ebook and it was full of invisible "wrong" characters.)

My solution was to switch my Mac keyboard from Unicode to U.S. English.

it is similar for me as well after copying the code from my email.
def update(self, k=1, step = 2):
if self.start.get() and not self.is_paused.get(): U+A0
x_data.append([i for i in range(0,k,1)][-1])
y = [i for i in range(0,k,step)][-1]
There is additional U+A0 character after checking with the tool as recommended by #Jacob Stern.

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