Wikipedia:Reference desk/Archives/Computing/2021 March 27

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March 27

Python: What is the difference between df.info() and df.info ?

import pandas as pd

data = [["Mark", 55, "Italy", 4.5, "Europe"],
        ["John", 33, "USA", 6.7, "America"],
        ["Tim", 41, "USA", 3.9, "America"],
        ["Jenny", 12, "Germany", 9.0, "Europe"]
        ];

df = pd.DataFrame(data=data, columns=["name", "age", "country", "score", "continent"],
                  index=[1001, 1000, 1002, 1003]);

print(df.info());

print("---------------Separation line------------------");

print(df.info);

Output:

<class 'pandas.core.frame.DataFrame'>
Int64Index: 4 entries, 1001 to 1003
Data columns (total 5 columns):
 #   Column     Non-Null Count  Dtype  
---  ------     --------------  -----  
 0   name       4 non-null      object 
 1   age        4 non-null      int64  
 2   country    4 non-null      object 
 3   score      4 non-null      float64
 4   continent  4 non-null      object 
dtypes: float64(1), int64(1), object(3)
memory usage: 192.0+ bytes
None
---------------Separation line------------------
<bound method DataFrame.info of        name  age  country  score continent
1001   Mark   55    Italy    4.5    Europe
1000   John   33      USA    6.7   America
1002    Tim   41      USA    3.9   America
1003  Jenny   12  Germany    9.0    Europe>

My question is that why do df.info() and df.info return different results? Thanks. Stringent Checker ^[bargaining] 10:13, 27 March 2021 (UTC)

info is a method that prints information about a DataFrame.

print(df.info()) calls the method info, which prints the information, then passes its return value (which is None) to print, so None is printed after the information.

print(df.info) takes the method info and, instead of calling the method, passes the method itself to print, thus printing <bound method DataFrame.info of [. . .]>. --116.86.4.41 (talk) 12:51, 27 March 2021 (UTC)

Thank you so much for the provided information!! I am managing to absorb it! Stringent Checker ^[bargaining] 13:06, 27 March 2021 (UTC)

Additional discovery: parentheses () in python pandas

I found that with or without a pair of parentheses did make a difference. It seems to be of some general rules of Python that I haven't figured out. I am new to Python Pandas_(software). @@

I substituted pandas for Python because the working memory just reminded me that I didn't seem to have encountered such an issue over the past month of learning Python. I have recently started learning to use pandas with Python.

# "reset_index" turns the index into a column,
# replacing the index with the default index.

import pandas as pd

data = [["Mark", 55, "Italy", 4.5, "Europe"],
        ["John", 33, "USA", 6.7, "America"],
        ["Tim", 41, "USA", 3.9, "America"],
        ["Jenny", 12, "Germany", 9.0, "Europe"]
        ];

df = pd.DataFrame(data=data, columns=["name", "age", "country", "score", "continent"],
                  index=[1001, 1000, 1002, 1003]);

print(df);

df.index.name = "user_id";

print("\n", df);

df.reset_index();

print("\n", df);

df = df.reset_index();

print("\n", df);

Output:

       name  age  country  score continent
1001   Mark   55    Italy    4.5    Europe
1000   John   33      USA    6.7   America
1002    Tim   41      USA    3.9   America
1003  Jenny   12  Germany    9.0    Europe

           name  age  country  score continent
user_id                                      
1001      Mark   55    Italy    4.5    Europe
1000      John   33      USA    6.7   America
1002       Tim   41      USA    3.9   America
1003     Jenny   12  Germany    9.0    Europe

           name  age  country  score continent
user_id                                      
1001      Mark   55    Italy    4.5    Europe
1000      John   33      USA    6.7   America
1002       Tim   41      USA    3.9   America
1003     Jenny   12  Germany    9.0    Europe

    user_id   name  age  country  score continent
0     1001   Mark   55    Italy    4.5    Europe
1     1000   John   33      USA    6.7   America
2     1002    Tim   41      USA    3.9   America
3     1003  Jenny   12  Germany    9.0    Europe

Stringent Checker ^[bargaining] 12:34, 27 March 2021 (UTC)

Linux system update broke mouse cursor

I recently ran a system update on my Fedora 32 Linux system, which updated the kernel from 5.10.18-100 to 5.11.7-100. When I rebooted and the new kernel started, my mouse cursor turned into a complete mess. Everything else worked OK. I rebooted again back to the old kernel, and the mouse cursor is all OK now. Did the kernel update somehow break the mouse cursor? And if so, why? Has this happened for anyone else? JIP | Talk 20:24, 27 March 2021 (UTC)

You mean the cursor was displayed as garbage? This is likely an issue with the driver for your graphics adapter. Drivers go in the kernel (either built-in or loaded as kernel modules), so that would explain why it happened. I guess the first step would be to check whether anyone else has reported this issue. If not, it's a bug that should be reported. Try a Web search for something like "fedora check graphics driver" if you don't know how to find out your driver. --47.155.96.47 (talk) 22:49, 31 March 2021 (UTC)

Image burned into monitor?

Just today evening, I was using my Fedora 32 system with a HP 24w monitor when I saw the image on the screen had developed weird vertical stripes and was flashing. I moved a few windows around and saw that the old windows remained on the screen as ghost images. They remained there when I logged off, and even remained when I restarted the whole system. What was even weirder was that when I disconnected the whole video cable, the screen still showed the ghost image of the Linux system even though it wasn't receiving any input any more.

As time passed, the ghost image started to fade away, and after a couple of hours, disappeared entirely and the screen is working all OK now.

What could have caused this? JIP | Talk 21:47, 27 March 2021 (UTC)

I know nothing about HP monitors, but I'm guessing this is a case of image persistence (though the relevant article does say that "the effects are... often not visible without close inspection," which sounds far milder than your case). — TheHardestAspect­OfCreatingAnAccount­IsAlwaysTheUsername: posted at 09:28, 28 March 2021 (UTC)

Anecdotally, I've seen that vertical striping and severe image persistence happen on aging TFT-LCD based monitors a few times. Just a symptom of them getting old, I suspect. 72.89.120.120 (talk) 09:42, 28 March 2021 (UTC)

@JIP: Your monitor seems to be a standard IPS panel with LED backlight.[1] It is possible that the capacitors on the controller board/power supply are going bad. If it happens again, you might consider trying a replacement board - could be as little as £10-20, and if you get a local PC shop to do it, it shouldn't be more than an hour's work. Otherwise it might be time to start looking for a new monitor. MinorProphet (talk) 23:19, 28 March 2021 (UTC)

I remember the days of monitors with TV tubes when you might have WordStar burned into the screen. Bubba73 ^{You talkin' to me?} 06:08, 29 March 2021 (UTC)