I have a data frame like so. I am trying to make a plot with the mean of 'number' for each year on the y and the year on the x. I think what I have to do to do this is make a new data frame with 2 columns 'year' and 'avg number' for each year. How would I go about doing that?
year number
0 2010 40
1 2010 44
2 2011 33
3 2011 32
4 2012 34
5 2012 56
When opening a question about pandas please make sure you following these guidelines: How to make good reproducible pandas examples. It will help us reproduce your environment.
Assuming your dataframe is stored in the df variable:
df.groupby('year').mean().plot()
Related
This question already has answers here:
Get the row(s) which have the max value in groups using groupby
(15 answers)
Closed 10 months ago.
New to the Python world and I'm working through a problem where I need to pull a value for the largest index value for each year. Will provide a table example and explain further
Year
Index
D_Value
2010
13
85
2010
14
92
2010
15
76
2011
9
68
2011
10
73
2012
100
94
2012
101
89
So, the desired output would look like this:
Year
Index
D_Value
2010
15
76
2011
10
73
2012
101
89
I've tried researching how to apply max() and .loc() functions, however, I'm not sure what the optimal approach is for this scenario. Any help would be greatly appreciated. I've also included the below code to generate the test table.
import pandas as pd
data = {'Year':[2010,2010,2010,2011,2011,2012,2012],'Index':[13,14,15,9,10,100,101],'D_Value':[85,92,76,68,73,94,89]}
df = pd.DataFrame(data)
print(df)
You can use groupby + rank
df['Rank'] = df.groupby(by='Year')['Index'].rank(ascending=False)
print(df[df['Rank'] ==1])
I have this pandas data frame, where I want to make a line plot, per each year strata:
year month canasta
0 2011 1 239.816531
1 2011 2 239.092353
2 2011 3 239.332308
3 2011 4 237.591538
4 2011 5 238.384231
... ... ... ...
59 2015 12 295.578605
60 2016 1 296.918861
61 2016 2 296.398701
62 2016 3 296.488780
63 2016 4 300.922927
And I tried this code:
dca.groupby(['year', 'month'])['canasta'].mean().reset_index().plot()
But I get this result:
I must be doing something wrong. Please, could you help me with this plot? The x axis is the months, and there should be a line per each year.
Why: Because after you do reset_index, year and month become normal columns. And some_df.plot() simply plots all the columns of the dataframe into one plot, resulting what you posted.
Fix: Try unstack instead of reset_index:
(dca.groupby(['year', 'month'])
['canasta'].mean()
.unstack('year').plot()
)
I have a data frame containing the daily CO2 data since 2015, and I would like to produce the monthly mean data for each year, then put this into a new data frame. A sample of the data frame I'm using is shown below.
month day cycle trend
year
2011 1 1 391.25 389.76
2011 1 2 391.29 389.77
2011 1 3 391.32 389.77
2011 1 4 391.36 389.78
2011 1 5 391.39 389.79
... ... ... ... ...
2021 3 13 416.15 414.37
2021 3 14 416.17 414.38
2021 3 15 416.18 414.39
2021 3 16 416.19 414.39
2021 3 17 416.21 414.40
I plan on using something like the code below to create the new monthly mean data frame, but the main problem I'm having is indicating the specific subset for each month of each year so that the mean can then be taken for this. If I could highlight all of the year "2015" for the month "1" and then average this etc. that might work?
Any suggestions would be hugely appreciated and if I need to make any edits please let me know, thanks so much!
dfs = list()
for l in L:
dfs.append(refined_data[index = 2015, "month" = 1. day <=31].iloc[l].mean(axis=0))
mean_matrix = pd.concat(dfs, axis=1).T
I would like to plot a stacked bar plot from a csv file in python. I have three columns of data
year word frequency
2018 xyz 12
2017 gfh 14
2018 sdd 10
2015 fdh 1
2014 sss 3
2014 gfh 12
2013 gfh 2
2012 gfh 4
2011 wer 5
2010 krj 4
2009 krj 4
2019 bfg 4
... 300+ rows of data.
I need to go through all the data and plot a stacked bar plot which is categorized based on the year, so x axis is word and y axis is frequency, the legend color should show year wise. I want to see how the evolution of each word occured year wise. Some of the technology words are repeatedly used in every year and hence the stack bar graph should add the values on top and plot, for example the word gfh initially plots 14 for year 2017, and then in year 2014 I want the gfh word to plot (in a different color) for a value of 12 on top of the gfh of 2017. How do I do this? So far I called the csv file in my code. But I don't understand how could it go over all the rows and stack the words appropriately (as some words repeat through all the years). Any help is highly appreciated. Also the years are arranged in random order in csv but I sorted them year wise to make it easier. I am just learning python and trying to understand this plotting routine since i have 40 years of data and ~20 words. So I thought stacked bar plot is the best way to represent them. Any other visualisation method is also welcome.
This can be done using pandas:
import pandas as pd
df = pd.read_csv("file.csv")
# Aggregate data
df = df.groupby(["word", "year"], as_index=False).agg({"frequency": "sum"})
# Create list to sort by
sorter = (
df.groupby(["word"], as_index=False)
.agg({"frequency": "sum"})
.sort_values("frequency")["word"]
.values
)
# Pivot, reindex, and plot
df = df.pivot(index="word", columns="year", values="frequency")
df = df.reindex(sorter)
df.plot.bar(stacked=True)
Which outputs:
I have a question. I am dealing with a Datetime DataFrame in Pandas. I want to perform a count on a particular column and group by the month.
For example:
df.groupby(df.index.month)["count_interest"].count()
Assuming that I am analyzing a Data From December 2019. I get a result like this
date
1 246
2 360
3 27
12 170
In reality, December 2019 is supposed to come first. Please what can I do because when I plot the frame grouped by month, the December 2019 is showing at the last and this is practically incorrect.
See plot below for your understanding:
You can try reindex:
df.groupby(df.index.month)["count_interest"].count().reindex([12,1,2,3])