Using python to input into a csv file

Question

I have data in this format:

2017-08-01,5.6
2017-09-01,5.6
2017-10-01,5.6
2017-11-01,5.5
2017-12-01,5.5
2018-01-01,5.4
2018-02-01,5.4

This data variable was created in this way:

data= fred.get_series('LMUNRRTTDEM156S').to_csv()

I have successfully inserted the data into separate columns and rows in a csv file but how could i filter the data variable to say: "only write the rows with a date later than 2010-01-01"? Also how can i define column names, i tried a simple write f.write('col1', 'col2') but this failed?

with open("fileName.csv", "w") as f:
    f.write(data)
    f.close()

Full code:

from fredapi import Fred
import csv
import pandas as pd

fred= Fred(api_key= 'XYZ')
data= fred.get_series('LMUNRRTTDEM156S').to_csv()

with open("fileName.csv", "w") as f:
    #f.write('hello', 'world')
    f.write(data)
    f.close()

Any help would be greatly appreciated

data is a string so, can you share how you built it ? edit your post and add more code — azro
– azro, Commented May 18, 2021 at 10:50
Are we to assume that you are using this API? github.com/mortada/fredapi/tree/master/fredapi In which case the get_series data returns a Pandas Series object — scotty3785
– scotty3785, Commented May 18, 2021 at 10:55

scotty3785 · Accepted Answer · 2021-05-18 11:12:04Z

0

According to the fredapi source code, you can specify an observation_start parameter to the get_series method.

I'd try the following

fred.get_series('LMUNRRTTDEM156S', observation_start="2010-01-01").to_csv('filename.csv')

This should filter the data to only show observations after the specified date.

To add a header, specify this when you output the csv

fred.get_series('LMUNRRTTDEM156S', observation_start="2010-01-01").to_csv('filename.csv', header=['Date','Values'])

edited May 18, 2021 at 11:12

answered May 18, 2021 at 11:04

scotty3785

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2 Comments

daniel stafford Over a year ago

i get a ValueError: Writing 1 cols but got 2 aliases when i use your second code insert ie the one with the header=['Date','Values']. Thanks again

scotty3785 Over a year ago

@danielstafford Oops! try header=['Value'], index_label='Date' as the arguments instead

azro · Accepted Answer · 2021-05-18 16:08:00Z

0

Use

observation_start param to specify the date from which retrieve the data
use header and index_label to name the columns for the csv dumping

from fredapi import Fred

fred = Fred(api_key=API_KEY)
data = fred.get_series('LMUNRRTTDEM156S', observation_start="2010-01-01")

data.to_csv('filename2.csv', header=['value'], index_label='date')

File will be like

date,value
2010-01-01,8.0
2010-02-01,8.0
2010-03-01,8.0

To join multiple Series use pandas.concat

data = fred.get_series('LMUNRRTTDEM156S', frequency='m', observation_start="2010-01-01")
data1 = fred.get_series('DEUCPIALLMINMEI', frequency='m', observation_start="2010-01-01")

df = pd.concat([data, data1], axis=1).rename(columns={0: 'Germany Unemployment', 1: 'Germany Inflation'})
df.to_csv('german.csv', index_label="date")

DataFrame.fillna can be useful in case one Series have some missing values

df.fillna(0).to_csv('german.csv', index_label="date")

Giving

date,Germany Unemployment,Germany Inflation
2010-01-01,8.0,92.3591431905318
2010-02-01,8.0,92.732311445847
2010-03-01,8.0,93.1987717649912

edited May 18, 2021 at 16:08

answered May 18, 2021 at 10:55

azro

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5 Comments

scotty3785 Over a year ago

Since the OP seems to be using the "fredapi" the data that they have is already a pandas Series object so converting the raw text back to a Dataframe isn't necessary.

azro Over a year ago

@scotty3785 yep just saw that, I'm editing

daniel stafford Over a year ago

@scotty3785 thanks for all the help. I was wondering, with 2 series from the FRED API how could I put them both into the same csv file and maintain the ordering based on the associated date, ie the new csv file would have 3 columns, 1 for date(the PK), second the attribute from series1 and third for the attribute in series3. To be clear: series1 format: date, attribute. series2 format: date, attribute.

daniel stafford Over a year ago

i currently have the code to retrieve the 2 series but unsure how to merge them on their date: from fredapi import Fred import pandas as pd fred= Fred(api_key= 'API_KEY') data = fred.get_series('LMUNRRTTDEM156S', frequency = 'm', observation_start="2010-01-01") data.to_csv('germanU.csv', header=['Germany Unemployment'], index_label='date') data1 = fred.get_series('DEUCPIALLMINMEI', frequency = 'm', observation_start="2010-01-01") data1.to_csv('germanInflation.csv', header=['Germany Inflation'], index_label='date')

scotty3785 Over a year ago

@danielstafford Sound like a new question to me. And this isn't my answer, it is from azro.

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