I have a list of dictionaries
d = [{'value':'foo_1', 'word_list':['blah1', 'blah2']}, ...., {'value': 'foo_n', 'word_list':['meh1', 'meh2']}]
I want to write this to a CSV file with all the 'value' keys in one column, and then each individual word from the "value"'s word_list as its own column. So I have the first row as
foo_1 blah_1 blah_2
and so on.
I don't know how many dictionaries I have, or how many words I have in "word_list".
How would I go about doing this in Python 3?
Thanks!
I figured out a solution, but it's kind of messy (wow, I can't write a bit of code without it being in the "proper format"...how annoying):
with open('filename', 'w') as f:
for key in d.keys():
f.write("%s,"%(key))
for word in d[key]:
f.write("%s,"%(word))
f.write("\n")
You can loop through the dictionaries one at a time, construct the list and then use the csv module to write the data as I have shown here
import csv
d = [{'value':'foo_1', 'word_list':['blah1', 'blah2']}, {'value': 'foo_n', 'word_list':['meh1', 'meh2']}]
with open('test_file.csv', 'w') as file:
writer = csv.writer(file)
for val_dict in d:
csv_row = [val_dict['value']] + val_dict['word_list']
writer.writerow(csv_row)
It should work for word lists of arbitrary length and as many dictionaries as you want.
It would probably be easiest to flatten each row into a normal list before writing it to the file. Something like this:
with open(filename, 'w') as file:
writer = csv.writer(file)
for row in data:
out_row = [row['value']]
for word in row['word_list']:
out_row.append(word)
csv.writerow(out_row)
# Shorter alternative to the two loops:
# csv.writerow((row['value'], *row['word_list']) for row in data)
Related
I wrote the following code to split my data matrix into a csv file:
f = open('midi_data.csv', 'w', newline="")
writer = csv.writer(f, delimiter= ',',quotechar =',',quoting=csv.QUOTE_MINIMAL)
for item in data:
writer.writerow(item)
print(item)
f.close()
But the csv file ends up looking like this:
tuples not separated by columns but by commas in one column only
What am I doing wrong?
The data seems to be written correctly inside the tuples, because when running the code it outputs the following:
enter image description here
I have this script that reads a CSV and saves the second column to a list, I'm trying to get it to write the contents of the list to a new CSV. The problem is every entry should have its own row but the new file sets everything into the same row.
I've tried moving the second with open code to within the first with open and I've tried adding a for loop to the second with open but no matter what I try I don't get the right results.
Here is the code:
import csv
col_store=[]
with open('test-data.csv', 'r') as rf:
reader = csv.reader(rf)
for row in reader:
col_store.append(row[1])
with open('meow.csv', 'wt') as f:
csv_writer = csv.writer(f)
csv_writer.writerows([col_store])
In your case if you have a column of single letters/numbers then Y.R answer will work.
To have a code that works in all cases, use this.
with open('meow.csv', 'wt') as f:
csv_writer = csv.writer(f)
csv_writer.writerows(([_] for _ in col_store))
From here it is mentioned that writerows expect an an iterable of row objects. Every row object should be an iterable of strings or numbers for Writer objects
The problem is that you are using 'writerows' treating 'col_store' as a list with one item.
The simplest approach to fixing this is calling
csv_writer.writerows(col_store)
# instead of
csv_writer.writerows([col_store])
However, this will lead to a probably unwanted result - having blank lines between the lines.
To solve this, use:
with open('meow.csv', 'wt', newline='') as f:
csv_writer = csv.writer(f)
csv_writer.writerows(col_store)
For more about this, see CSV file written with Python has blank lines between each row
Note: writerows expects 'an iterable of row objects' and 'row objects must be an interable of strings or numbers'.
(https://docs.python.org/3/library/csv.html)
Therefore, in the generic case (trying to write integers for examlpe), you should use Sam's solution.
I have a list of lists containing a varying number of strings in each sublist:
tq_list = [['The mysterious diary records the voice.', 'Italy is my favorite country', 'I am happy to take your donation', 'Any amount will be greatly appreciated.'], ['I am counting my calories, yet I really want dessert.', 'Cats are good pets, for they are clean and are not noisy.'], ['We have a lot of rain in June.']]
I would like to create a new CSV file for each sublist. All I have so far is a way to output each sublist as a row in the same CSV file using the following code:
name_list = ["sublist1","sublist2","sublist3"]
with open("{}.csv".format(*name_list), "w", newline="") as f:
writer = csv.writer(f)
for row in tq_list:
writer.writerow(row)
This creates a single CSV file named 'sublist1.csv'.
I've toyed around with the following code:
name_list = ["sublist1","sublist2","sublist3"]
for row in tq_list:
with open("{}.csv".format(*name_list), "w", newline="") as f:
writer = csv.writer(f)
writer.writerow(row)
Which also only outputs a single CSV file named 'sublist1.csv', but with only the values from the last sublist. I feel like this is a step in the right direction, but obviously not quite there yet.
What the * in "{}.csv".format(*name_list) in your code actually does is this: It unpacks the elements in name_list to be passed into the function (in this case format). That means that format(*name_list) is equivalent to format("sublist1", "sublist2", "sublist3"). Since there is only one {} in your string, all arguments to format except "sublist1" are essentially discarded.
You might want to do something like this:
for index, row in enumerate(tq_list):
with open("{}.csv".format(name_list[index]), "w", newline="") as f:
...
enumerate returns a counting index along with each element that it iterates over so that you can keep track of how many elements there have already been. That way you can write into a different file each time. You could also use zip, another handy function that you can look up in the Python documentation.
I am trying read a CSV file into python 3 using unicodecsv library. Code follows :
with open('filename.csv', 'rb') as f:
reader = unicodecsv.DictReader(f)
Student_Data = list(reader)
But the order of the columns in the CSV file is not retained when I output any element from the Student_Data. The output contains any random order of the columns. Is there anything wrong with the code? How do I fix this?
As stated in csv.DictReader documentation, the DictReader object behaves like a dict - so it is not ordered.
You can obtain the list of the fieldnames with:
reader.fieldnames
But if you only want to obtain a list of the field values, in original order, you can just use a normal reader:
with open('filename.csv', 'rb') as f:
reader = unicodecsv.reader(f)
for row in reader:
Student_Data = row
I have an excel sheet like this:
I would like to output the data into an excel file like this:
Basically, for the common elements in column 2,3,4, I want to contacenate the values in the 5th column.
Please suggest, how could I do this ?
The easiest way to approach an issue like this is exporting the spreadsheet to CSV first, in order to help ensure that it imports correctly into Python.
Using a defaultdict, you can create a dictionary that has unique keys and then iterate through lines adding the final column's values to a list.
Finally you can write it back out to a CSV format:
from collections import defaultdict
results = defaultdict(list)
with open("in_file.csv") as f:
header = f.readline()
for line in f:
cols = line.split(",")
key = ",".join(cols[0:4])
results[key].append(cols[4])
with open("out_file.csv", "w") as f:
f.write(header)
for k, v in results.iteritems():
line = '{},"{}",\n'.format(k, ", ".join(v))
f.write(line)