How to print a specific line from a file

Question

I am trying to print a specific line from the file "Scores", which is option B. This is my code:

print("Option A: Show all scores\nOption B: Show a record\nOption Q: Quit")
decision = input("Enter A, B, C or Q: ")
myFile = open("Scores.txt", "rt")
if decision == "A":
    record = myFile.read()
    print(record)
    myFile.close()
elif decision == "B" or decision == "b":
    playerName = input("Enter a player name to view their scores: ")
    record = myFile.read()
    answer = record.find(playerName)
    for line in answer:
        print(line)
elif decision == "Q" or decision == "q":
    exit

I went for Option B, then I entered a player name that holds the score of the player, but it throws this error message:

line 12, in <module>
for line in answer():
TypeError: 'int' object is not callable

@PadraicCunningham At school, we haven't learned about using dictionaries. But thanks for the suggestion! — User0123456789, Apr 18 '16 at 17:45
No worries,`elif decision == "Q" or "q":` also does not do what you think. You want `elif decision == "Q" or decision == "q":` or more simply `elif decision.lower() == "q"` — Padraic Cunningham, Apr 18 '16 at 17:47
BTW, your typerror is caused by `answer()`, as answer is not a function — Dmiters, Apr 18 '16 at 17:47
@PadraicCunningham Whoops, that was a mistake. Thanks for that! — User0123456789, Apr 18 '16 at 17:48

mvelay · Answer 1 · 2016-04-24T19:04:43.110

3

find() method returns a positive index if it succeeds, -1 otherwise

You should loop on your content line by line, as follows:

for line in myFile:
    if line.find(playerName):
        print(line)

edited Apr 24 '16 at 19:04

answered Apr 18 '16 at 17:41

mvelay

1,520
1
10
23

`read` retuns one string. So you will iterate characters instead of lines. Change to `record.split('\n')` – romants Apr 18 '16 at 17:42
This would match `"foo"` with `"foobar"` – Padraic Cunningham Apr 18 '16 at 17:43
It prints the whole file... Am I putting that for loop in the right place? I replaced `for line in answer:` with the bit of code you just put up – User0123456789 Apr 18 '16 at 17:54
I have just edited my answer using readlines() instead of read(), it could fix the issue – mvelay Apr 18 '16 at 18:04

score 3 · Accepted Answer · answered Apr 23 '16 at 07:11

3

A few cents from my side :

file = open("file")
lines = file.readlines()
for line in lines:
    if playername in line:
        print line

file.close()

Hope it works!

answered Apr 23 '16 at 07:11

Vin

729
9
15

score 2 · Answer 3 · answered Apr 25 '16 at 18:14

A safer way to read the file and find data, so that you will not have OutOfMemory issues when storing the whole file in memory.

playerName = input("Enter a player name to view their scores: ")
with open("Scores.txt", 'r') as f:
    for row in f:
        if playerName in row:
            print row

This way you will be using with that will close the file by itself either when the program ends or Garbage Collection kicks in. This way python will read the file line by line and store only 1 line in memory. So you can use huge files and do not worry about memory issues.

Hope it helps :)

score 1 · Answer 4 · answered Apr 18 '16 at 18:05

1

Working with str methods will take more acrobatics. Try the following,

import re
p = re.compile(r"\b{}\b".format(playername)) # keep it ready

# inside option B
for line in myfile:    # no need to `.read()` it
    match = p.search(line)
    if match:
        print(line)
        break   # if there is only one record for playername

See if it works for you.

answered Apr 18 '16 at 18:05

C Panda

3,297
2
11
11

It ended the program – User0123456789 Apr 20 '16 at 19:54
@User0123456789 can you elaborate? – C Panda Apr 24 '16 at 19:44
@C Panda I put the first two lines of your piece of code outside the if and elif statements and replaced your for loop with `for line in answer: print(line)`. I saved the program and ran it, but when I searched for the player name "Ben", It just ended the program. Did I do the right thing? – User0123456789 Apr 25 '16 at 16:53

score 1 · Answer 5 · edited May 23 '17 at 10:27

1

similar thing here: Reading specific lines only (Python)

fp = open("file")
for i, line in enumerate(fp):
    if line == playername:
        print line

fp.close()

I also notice you don't close your file for each decision, should make that happen.

edited May 23 '17 at 10:27

Community

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1

answered Apr 22 '16 at 19:33

Alex Durbin

196
1
7

score 1 · Answer 6 · answered Apr 27 '16 at 17:41

Few python idioms and small optimization

Here are many answer, my sample brings in few python idioms and optimize it a bit:

fname = "Scores.txt"
player_name = "Quido"

with open(fname) as f:
    for line in f:
        if player_name in line:
            print line
            break
print "Going on doing following tasks."

The with block will close the open file on exiting the inner block. No need to f.close(), safe in case of problems to read the file.

for line in f: shows, that iterating over file open in text mode we get one line per iteration.

break after we print the line with the player will effectively stop iterating over lines assuming, there is only one such line or that we are happy with the very first one. If this is not the case, removing the break allows printing all lines containing the player name.

As lines returned from text file iterator contain new line, you may prefer to get rid of them. Use print line.strip() in such case what will remove all blank characters from start and end of the line.

Final print is proving, the program continues after it processes all the lines.

It may happen, that you get no output for name, which appears to be present in the file. In such a case, you might need to clarify letter case. For example, if your text file contains all the names in exact casing, you have to enter the name properly.

Other option is to lower-case the player_name and compare it against lower cased line:

fname = "Scores.txt"
player_name = "Quido"
normalized_player_name = player_name.lower()

with open(fname) as f:
    for line in f:
        if normalized_player_name in line.lower():
            print line.strip()
            break  # comment out to print all lines with the player
print "Going on doing following tasks."

Note, that we normalize the player_name outside from the loop to be a bit faster. Lower-casing inside the loop would work, but would do the same task repeatedly.

The line is printed using exact letter cases as in the file.

How to print a specific line from a file

6 Answers6

Few python idioms and small optimization

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