count = 1
maxcount = 6
while(count <= maxcount):
print locals()["test_"+str(count)]+str(".png")
count += 1
I was hoping for the output
test_1.png
test_2.png
test_3.png
test_4.png
test_5.png
test_6.png
Instead I get an error
KeyError: 'test_1'
Also, is it possible to add a 0 after the _ if the value is less than 10?
I am using this loop for saving files, but figured that this MWE would be less labour and would easily apply to my issue
You are getting that error because you have not created a variable named 'test_1' in your local scope. Instead of using a while loop, it is easier to use a for loop. Also, there's a thing called string formatting, which is easier to use than string concatenation.
maxcount = 6
for i in range(1, maxcount+1):
filename = 'test_{}.png'.format(i)
with open(filename, 'r') as f:
# do stuff
Related
a = 1
for i in range(5):
browser.find_element_by_xpath("/html/body/div[6]/div/div/div[2]/div/div/div[1]/div[3]/button").click()
sleep(1)
I want to increase the 1 in div[1] by 1+ every loop, but how can i do that?
i thought i need to add a value, do "+a+" and last of all a "a = a + 1" to increase the value every time, but it didnt worked.
a = 1
for i in range(5):
browser.find_element_by_xpath("/html/body/div[6]/div/div/div[2]/div/div/div["+a+"]/div[3]/button").click()
a = a + 1
sleep(1)
for i in range(1,6):
browser.find_element_by_xpath("/html/body/div[6]/div/div/div[2]/div/div/div["+str(i)+"]/div[3]/button").click()
sleep(1)
you don't need 2 variables, just one variable i in the loop, convert it to string with str() and add it to where you need it, pretty simple. the value of i increases for every iteration of the loop going from 1 to 5 doing exactly what you need.
alternatively to Elyes' answer, you can use the 'global' keyword at the top of your function then a should increment 'correctly'.
You don't really need two variables for this unless you are going to use the second variable for something. However, look at the following code and it will show you that both i and a will give you the same result:
from time import sleep
a = 1
for i in range(1, 6):
path = "/html/body/div[6]/div/div/div[2]/div/div/div[{idx}]/div[3]/button".format(idx=i)
print(path, 'using i')
path = "/html/body/div[6]/div/div/div[2]/div/div/div[{idx}]/div[3]/button".format(idx=a)
a += 1
print(path, 'using a')
sleep(1)
Result:
/html/body/div[6]/div/div/div[2]/div/div/div[1]/div[3]/button using i
/html/body/div[6]/div/div/div[2]/div/div/div[1]/div[3]/button using a
/html/body/div[6]/div/div/div[2]/div/div/div[2]/div[3]/button using i
/html/body/div[6]/div/div/div[2]/div/div/div[2]/div[3]/button using a
/html/body/div[6]/div/div/div[2]/div/div/div[3]/div[3]/button using i
/html/body/div[6]/div/div/div[2]/div/div/div[3]/div[3]/button using a
/html/body/div[6]/div/div/div[2]/div/div/div[4]/div[3]/button using i
/html/body/div[6]/div/div/div[2]/div/div/div[4]/div[3]/button using a
/html/body/div[6]/div/div/div[2]/div/div/div[5]/div[3]/button using i
/html/body/div[6]/div/div/div[2]/div/div/div[5]/div[3]/button using a
You can read up on range here
Exporting the data:
num = 0
exportData = open("results_file.txt", "a")
while num < len(runs) - 1:
exportData.write(str(runs[num]) + "\n")
num = num + 1
exportData.close()
Importing the data into the new file:
runs = []
num = 1
count = len(open("results_file.txt").readlines( ))
print(count)
importData = open("results_file.txt", "r")
while num < count:
runs.append(importData.read(num))
print(importData.read(num))
num = num + 1
importData.close()
My goal is to export the array of integers to a file (can be something else than a txt file for all I care) and then to import them at a later date into a new file and use them there as integers (performing mathematical operations on them)
The error that I'm getting (on line 28 I'm trying to use the first number in the array for a mathematical calculation):
line 28, in if runs[num] < 7: TypeError: '<' not supported between instances of 'str' and 'int'
runs = []
num = 1
count = len(open("results_file.txt").readlines( ))
print(count)
importData = open("results_file.txt", "r")
while num < count:
runs.append(int(importData.read(num)))
print(importData.read(num))
num = num + 1
importData.close()
Adding int() returns this error:
ValueError: invalid literal for int() with base 10: '4\n1'
You're not being pythonic, and many of the answers here aren't either. So, let me clean up your code a bit.
from ast import literal_eval
with open("results_file.txt", "a") as exportData:
for run in runs:
exportData.write(str(run) + "\n")
runs = []
with open("results_file.txt", "r") as importData:
runs.extend([literal_eval(x) for x in importData])
I'll break this down line by line:
from ast import literal_eval is the safest way to parse things that are strings into python objects. It's better than using a plain old eval because it won't run arbitrary code. We'll use this function to read the data latter.
with open(...) as ... is the best way to open a file. It contains the file-object within a single scope and catches errors. Look this one up here: Pep 343
for ... in ... For loops that you're using are not pythonoic at all. The pythonic way is to use iterators no need to count lines and declare variables to keep track... the python objects keep track of themselves. (If you need a counter I highly recommend that you look up enumerate() Enumerate() in Python
exportData.write(str(run) + "\n") only change here is that with the pythonic for loop there's no need to index the runs list anymore.
runs = [] I think you know what this is, but I have to declare it out of the with statement because if the with statement throws an error, and you were to catch it, runs will be initialized.
I've already discussed with statements.
runs.extend([literal_eval(x) for x in importData]) Has two things going on. extend appends a list to a list... cool. The more interesting part here is the list comprehension. Here's a tutorial on list comprehensions. As soon as you get comfortable with the for loops, the list comprehension is the next pythonic step. For further pythonic enlightenment, this line could also be replaced with: runs.extend(map(literal_eval, importData))
That's it, 9 lines. Happy hacking.
The error you are experiencing is most likely due to the fact you're trying to add a string to an integer. Try doing
runs = []
num = 1
count = len(open("results_file.txt").readlines( ))
print(count)
importData = open("results_file.txt", "r")
while num < count:
runs.append(int(importData.read(num)))
print(importData.read(num))
num = num + 1
importData.close()
The main function/tool you're looking for is int(). For example:
>>> int('15')
15
>>> int('15') + 5
20
But you also can save yourself some real headaches by coding this differently. For example, you do not need to know the number of lines ahead of time. You can just call .readline() until it returns an empty string. Or even iterate over the file and when it ends, it with exit.
Another tip, and this is just good practice, is to use the context manager for opening files. So instead of
file = open('myfile.txt')
for line in file:
print(line)
you would do:
with open('myfile.txt') as file:
for line in file:
print(line)
The big advantage of the latter is that if will always make sure file is closed properly. This is especially helpful when writing to a file.
I'm trying to increase the count of an integer given that an if statement returns true. However, when this program is ran it always prints 0.I want n to increase to 1 the first time the program is ran. To 2 the second time and so on.
I know functions, classes and modules you can use the global command, to go outside it, but this doesn't work with an if statement.
n = 0
print(n)
if True:
n += 1
Based on the comments of the previous answer, do you want something like this:
n = 0
while True:
if True: #Replace True with any other condition you like.
print(n)
n+=1
EDIT:
Based on the comments by OP on this answer, what he wants is for the data to persist or in more precise words the variable n to persist (Or keep it's new modified value) between multiple runs times.
So the code for that goes as(Assuming Python3.x):
try:
file = open('count.txt','r')
n = int(file.read())
file.close()
except IOError:
file = open('count.txt','w')
file.write('1')
file.close()
n = 1
print(n)
n += 1
with open('count.txt','w') as file:
file.write(str(n))
print("Now the variable n persists and is incremented every time.")
#Do what you want to do further, the value of n will increase every time you run the program
NOTE:
There are many methods of object serialization and the above example is one of the simplest, you can use dedicated object serialization modules like pickle and many others.
If you want it to work with if statement only. I think you need to put in a function and make to call itself which we would call it recursion.
def increment():
n=0
if True:
n+=1
print(n)
increment()
increment()
Note: in this solution, it would run infinitely.
Also you can use while loop or for loop as well.
When you rerun a program, all data stored in memory is reset. You need to save the variable somewhere outside of the program, on disk.
for an example see How to increment variable every time script is run in Python?
ps. Nowadays you can simply do += with a bool:
a = 1
b = True
a += b # a will be 2
I've searched this error on here, but haven't seen anything that yet matches my situation (disclaimer, I'm still getting used to Python).
import os
os.chdir("C:\Projects\Rio_Grande\SFR_Checking") # set working directory
stressPeriod = 1
segCounter = 1
inFlow = 0
outFlow = 0
with open(r"C:\Projects\streamflow.dat") as inputFile:
inputList = list(inputFile)
while stressPeriod <= 1:
segCounter = 1
lineCounter = 1
outputFile = open("stats.txt", 'w') # Create the output file
for lineItem in inputList:
if (((stressPeriod - 1) * 11328) + 8) < lineCounter <= (stressPeriod * 11328):
lineItem = lineItem.split()
if int(lineItem[3]) == int(segCounter) and int(lineItem[4]) == int(1):
inFlow = lineItem[5]
outFlow = lineItem[7]
lineItemMem = lineItem
elif int(lineItem[3]) == int(segCounter) and int(lineItem[4]) <> int(1):
outFlow = lineItem[7]
else:
gainLoss = str(float(outFlow) - float(inFlow))
lineItemMem.append(gainLoss)
lineItemMem = ','.join(lineItemMem)
outputFile.write(lineItemMem + "\n") # write # lines to file
segCounter += 1
inFlow = lineItem[5]
outFlow = lineItem[7]
lineCounter += 1
outputFile.close()
So basically this program is supposed to read a .dat file and parse out bits of information from it. I split each line of the file into a list to do some math on it (math operations are between varying lines in the file, which adds complexity to the code). I then append a new number to the end of the list for a given line, and that's where things inexplicably break down. I get the following error:
Traceback (most recent call last):
File "C:/Users/Chuck/Desktop/Python/SFR/SFRParser2.py", line 49, in <module>
lineItemMem.append(gainLoss)
AttributeError: 'str' object has no attribute 'append'
When I give it a print command to test that lineItemMem is actually a list and not a string, it prints a list for me. If I put in code for
lineItemMem.split(",") to break the string, I get an error saying that list object has no attribute split. So basically, when I try to do list operations, the error says its a string, and when I try to do string operations, the error says it's a list. I've tried a fair bit of mucking around, but frankly can't tell what the problem is here. Any insight is appreciated, thanks.
I think the issue has to do with these lines:
lineItemMem.append(gainLoss)
lineItemMem = ','.join(lineItemMem)
Initially lineItemMem is a list, and you can append an item to the end of it. However, the join call you're doing turns the list into a string. That means the next time this part of the code runs, the append call will fail.
I'm not certain exactly what the best solution is. Perhaps you should use a different variable for the string version? Or maybe after you join the list items together into a single string and write that result out, you should reinitialize the lineItemMem variable to a new empty list? You'll have to decide what works best for your actual goals.
There are two places where lineItemMem is set. The first is this:
lineItem = lineItem.split()
# ...
lineItemMem = lineItem
where it is set to the result of a split operation, i.e. a List.
The second place is this:
lineItemMem = ','.join(lineItemMem)
here, it is set to the result of a join operation, i.e. a String.
So, the reason why the error sometimes states that it is a string and sometimes a list is, that that is acutally the case depending on the conditions in the if statement.
The code, as presented, is imho near undebuggable. Instead of tinkering, it would be a better approach to think about the different goals that should be achieved (reading a file, parsing the content, formatting the data, writing it to another file) and tackle them individually.
I have a problem in Python I simply can't wrap my head around, even though it's fairly simple (I think).
I'm trying to make "string series". I don't really know what it's called, but it goes like this:
I want a function that makes strings that run in series, so that every time the functions get called it "counts" up once.
I have a list with "a-z0-9._-" (a to z, 0 to 9, dot, underscore, dash). And the first string I should receive from my method is aaaa, next time I call it, it should return aaab, next time aaac etc. until I reach ----
Also the length of the string is fixed for the script, but should be fairly easy to change.
(Before you look at my code, I would like to apologize if my code doesn't adhere to conventions; I started coding Python some days ago so I'm still a noob).
What I've got:
Generating my list of available characters
chars = []
for i in range(26):
chars.append(str(chr(i + 97)))
for i in range(10):
chars.append(str(i))
chars.append('.')
chars.append('_')
chars.append('-')
Getting the next string in the sequence
iterationCount = 0
nameLen = 3
charCounter = 1
def getString():
global charCounter, iterationCount
name = ''
for i in range(nameLen):
name += chars[((charCounter + (iterationCount % (nameLen - i) )) % len(chars))]
charCounter += 1
iterationCount += 1
return name
And it's the getString() function that needs to be fixed, specifically the way name gets build.
I have this feeling that it's possible by using the right "modulu hack" in the index, but I can't make it work as intended!
What you try to do can be done very easily using generators and itertools.product:
import itertools
def getString(length=4, characters='abcdefghijklmnopqrstuvwxyz0123456789._-'):
for s in itertools.product(characters, repeat=length):
yield ''.join(s)
for s in getString():
print(s)
aaaa
aaab
aaac
aaad
aaae
aaaf
...