Exercise 1. Life expectancy vs fertility - part 1

The Gapminder Foundation (www.gapminder.org) is a non-profit organization based in Sweden that promotes global development through the use of statistics that can help reduce misconceptions about global development.

Using ggplot and the points layer, create a scatter plot of life expectancy versus fertility for the African continent in 2012.

Remember that you can use the R console to explore the gapminder dataset to figure out the names of the columns in the dataframe.

In this exercise we provide parts of code to get you going. You need to fill out what is missing. But note that going forward, in the next exercises, you will be required to write most of the code.

library(dplyr)
## 
## Attaching package: 'dplyr'
## The following objects are masked from 'package:stats':
## 
##     filter, lag
## The following objects are masked from 'package:base':
## 
##     intersect, setdiff, setequal, union
library(ggplot2)
library(dslabs)
data(gapminder)
## fill out the missing parts in filter and aes
gapminder %>% filter(continent == "Africa" & year == 2012) %>%
  ggplot(aes(fertility,life_expectancy)) +
  geom_point()

Exercise 2. Life expectancy vs fertility - part 2 - coloring your plot

Note that there is quite a bit of variability in life expectancy and fertility with some African countries having very high life expectancies. There also appear to be three clusters in the plot.

Remake the plot from the previous exercises but this time use color to distinguish the different regions of Africa to see if this explains the clusters. Remember that you can explore the gapminder data to see how the regions of Africa are labeled in the data frame!

Use color rather than col inside your ggplot call - while these two forms are equivalent in R, the grader specifically looks for color.

library(dplyr)
library(ggplot2)
library(dslabs)
data(gapminder)
gapminder %>%
  filter(continent == "Africa", year == 2012) %>%
  ggplot(aes(fertility, life_expectancy, color = region )) +
  geom_point()

Exercise 3. Life expectancy vs fertility - part 3 - selecting country and region

While many of the countries in the high life expectancy/low fertility cluster are from Northern Africa, three countries are not.

Create a table showing the country and region for the African countries (use select) that in 2012 had fertility rates of 3 or less and life expectancies of at least 70.

Assign your result to a data frame called df.

library(dplyr)
library(dslabs)
data(gapminder)
df <- gapminder %>%
  filter(continent == "Africa" & year == 2012 & fertility <= 3 & life_expectancy >= 70) %>%
  select(country, region) 
df
##      country          region
## 1    Algeria Northern Africa
## 2 Cape Verde  Western Africa
## 3      Egypt Northern Africa
## 4      Libya Northern Africa
## 5  Mauritius  Eastern Africa
## 6    Morocco Northern Africa
## 7 Seychelles  Eastern Africa
## 8    Tunisia Northern Africa

Exercise 4. Life expectancy and the Vietnam War - part 1

The Vietnam War lasted from 1955 to 1975. Do the data support war having a negative effect on life expectancy? We will create a time series plot that covers the period from 1960 to 2010 of life expectancy for Vietnam and the United States, using color to distinguish the two countries. In this start we start the analysis by generating a table.

Use filter to create a table with data for the years from 1960 to 2010 in Vietnam and the United States.

Save the table in an object called tab.

library(dplyr)
library(dslabs)
data(gapminder)
countries <- c("Vietnam", "United States")
tab <- gapminder %>%
  filter(country %in% countries, year >= 1960 & year <= 2010) 
tab
##           country year infant_mortality life_expectancy fertility population
## 1   United States 1960             25.9           69.91      3.67  186176524
## 2         Vietnam 1960             75.6           58.52      6.35   32670623
## 3   United States 1961             25.4           70.32      3.63  189077076
## 4         Vietnam 1961             72.6           59.17      6.39   33666768
## 5   United States 1962             24.9           70.21      3.48  191860710
## 6         Vietnam 1962             69.9           59.82      6.43   34684164
## 7   United States 1963             24.4           70.04      3.35  194513911
## 8         Vietnam 1963             67.3           60.42      6.45   35722092
## 9   United States 1964             23.8           70.33      3.22  197028908
## 10        Vietnam 1964             61.7           60.95      6.46   36780984
## 11  United States 1965             23.3           70.41      2.93  199403532
## 12        Vietnam 1965             60.7           61.32      6.48   37860014
## 13  United States 1966             22.7           70.43      2.71  201629471
## 14        Vietnam 1966             59.9           61.36      6.49   38959335
## 15  United States 1967             22.0           70.76      2.56  203713082
## 16        Vietnam 1967             59.0           61.06      6.49   40074695
## 17  United States 1968             21.3           70.42      2.47  205687611
## 18        Vietnam 1968             58.2           60.45      6.49   41195833
## 19  United States 1969             20.6           70.66      2.46  207599308
## 20        Vietnam 1969             57.3           59.63      6.49   42309662
## 21  United States 1970             19.9           70.92      2.46  209485807
## 22        Vietnam 1970             56.4           58.78      6.47   43407291
## 23  United States 1971             19.1           71.24      2.27  211357912
## 24        Vietnam 1971             55.5           58.17      6.42   44485910
## 25  United States 1972             18.3           71.34      2.01  213219515
## 26        Vietnam 1972             54.7           58.00      6.35   45549487
## 27  United States 1973             17.5           71.54      1.87  215092900
## 28        Vietnam 1973             53.8           58.35      6.25   46604726
## 29  United States 1974             16.7           72.08      1.83  217001865
## 30        Vietnam 1974             52.8           59.23      6.13   47661770
## 31  United States 1975             16.0           72.68      1.77  218963561
## 32        Vietnam 1975             51.8           60.54      5.97   48729397
## 33  United States 1976             15.2           72.99      1.74  220993166
## 34        Vietnam 1976             50.9           62.07      5.80   49808071
## 35  United States 1977             14.5           73.38      1.78  223090871
## 36        Vietnam 1977             49.8           63.58      5.61   50899504
## 37  United States 1978             13.8           73.58      1.75  225239456
## 38        Vietnam 1978             48.8           64.86      5.42   52015279
## 39  United States 1979             13.2           74.03      1.80  227411604
## 40        Vietnam 1979             47.8           65.84      5.23   53169674
## 41  United States 1980             12.6           73.93      1.82  229588208
## 42        Vietnam 1980             46.8           66.49      5.05   54372518
## 43  United States 1981             12.1           74.36      1.81  231765783
## 44        Vietnam 1981             45.8           66.86      4.87   55627743
## 45  United States 1982             11.7           74.65      1.81  233953874
## 46        Vietnam 1982             44.8           67.10      4.69   56931822
## 47  United States 1983             11.2           74.71      1.78  236161961
## 48        Vietnam 1983             43.9           67.30      4.52   58277391
## 49  United States 1984             10.9           74.81      1.79  238404223
## 50        Vietnam 1984             43.0           67.51      4.36   59653092
## 51  United States 1985             10.6           74.79      1.84  240691557
## 52        Vietnam 1985             42.0           67.77      4.21   61049370
## 53  United States 1986             10.4           74.87      1.84  243032017
## 54        Vietnam 1986             41.0           68.07      4.06   62459557
## 55  United States 1987             10.2           75.01      1.87  245425409
## 56        Vietnam 1987             40.0           68.38      3.93   63881296
## 57  United States 1988             10.0           75.02      1.92  247865202
## 58        Vietnam 1988             38.9           68.68      3.81   65313709
## 59  United States 1989              9.7           75.10      2.00  250340795
## 60        Vietnam 1989             37.7           69.00      3.68   66757401
## 61  United States 1990              9.4           75.40      2.07  252847810
## 62        Vietnam 1990             36.6           69.30      3.56   68209604
## 63  United States 1991              9.1           75.50      2.06  255367160
## 64        Vietnam 1991             35.4           69.60      3.42   69670620
## 65  United States 1992              8.8           75.80      2.04  257908206
## 66        Vietnam 1992             34.3           69.80      3.26   71129537
## 67  United States 1993              8.5           75.70      2.02  260527420
## 68        Vietnam 1993             33.1           70.10      3.07   72558986
## 69  United States 1994              8.2           75.80      2.00  263301323
## 70        Vietnam 1994             32.0           70.30      2.88   73923849
## 71  United States 1995              8.0           75.90      1.98  266275528
## 72        Vietnam 1995             30.9           70.60      2.68   75198975
## 73  United States 1996              7.7           76.30      1.98  269483224
## 74        Vietnam 1996             29.9           70.90      2.48   76375677
## 75  United States 1997              7.5           76.60      1.97  272882865
## 76        Vietnam 1997             28.9           71.10      2.31   77460429
## 77  United States 1998              7.3           76.80      2.00  276354096
## 78        Vietnam 1998             27.9           71.50      2.17   78462888
## 79  United States 1999              7.2           76.90      2.01  279730801
## 80        Vietnam 1999             27.0           71.70      2.06   79399708
## 81  United States 2000              7.1           76.90      2.05  282895741
## 82        Vietnam 2000             26.1           72.00      1.98   80285563
## 83  United States 2001              7.0           76.90      2.03  285796198
## 84        Vietnam 2001             25.3           72.20      1.94   81123685
## 85  United States 2002              6.9           77.10      2.02  288470847
## 86        Vietnam 2002             24.6           72.50      1.92   81917488
## 87  United States 2003              6.8           77.30      2.05  291005482
## 88        Vietnam 2003             23.9           72.80      1.91   82683039
## 89  United States 2004              6.9           77.60      2.06  293530886
## 90        Vietnam 2004             23.2           73.00      1.90   83439812
## 91  United States 2005              6.8           77.60      2.06  296139635
## 92        Vietnam 2005             22.6           73.30      1.90   84203817
## 93  United States 2006              6.7           77.80      2.11  298860519
## 94        Vietnam 2006             22.0           73.50      1.89   84979667
## 95  United States 2007              6.6           78.10      2.12  301655953
## 96        Vietnam 2007             21.4           73.80      1.88   85770717
## 97  United States 2008              6.5           78.30      2.07  304473143
## 98        Vietnam 2008             20.8           74.10      1.86   86589342
## 99  United States 2009              6.4           78.50      2.00  307231961
## 100       Vietnam 2009             20.3           74.30      1.84   87449021
## 101 United States 2010              6.3           78.80      1.93  309876170
## 102       Vietnam 2010             19.8           74.50      1.82   88357775
##              gdp continent             region
## 1   2.479391e+12  Americas   Northern America
## 2             NA      Asia South-Eastern Asia
## 3   2.536417e+12  Americas   Northern America
## 4             NA      Asia South-Eastern Asia
## 5   2.691139e+12  Americas   Northern America
## 6             NA      Asia South-Eastern Asia
## 7   2.809549e+12  Americas   Northern America
## 8             NA      Asia South-Eastern Asia
## 9   2.972502e+12  Americas   Northern America
## 10            NA      Asia South-Eastern Asia
## 11  3.162743e+12  Americas   Northern America
## 12            NA      Asia South-Eastern Asia
## 13  3.368321e+12  Americas   Northern America
## 14            NA      Asia South-Eastern Asia
## 15  3.452529e+12  Americas   Northern America
## 16            NA      Asia South-Eastern Asia
## 17  3.618250e+12  Americas   Northern America
## 18            NA      Asia South-Eastern Asia
## 19  3.730416e+12  Americas   Northern America
## 20            NA      Asia South-Eastern Asia
## 21  3.737877e+12  Americas   Northern America
## 22            NA      Asia South-Eastern Asia
## 23  3.867133e+12  Americas   Northern America
## 24            NA      Asia South-Eastern Asia
## 25  4.080668e+12  Americas   Northern America
## 26            NA      Asia South-Eastern Asia
## 27  4.321881e+12  Americas   Northern America
## 28            NA      Asia South-Eastern Asia
## 29  4.299437e+12  Americas   Northern America
## 30            NA      Asia South-Eastern Asia
## 31  4.291009e+12  Americas   Northern America
## 32            NA      Asia South-Eastern Asia
## 33  4.523528e+12  Americas   Northern America
## 34            NA      Asia South-Eastern Asia
## 35  4.733337e+12  Americas   Northern America
## 36            NA      Asia South-Eastern Asia
## 37  4.999656e+12  Americas   Northern America
## 38            NA      Asia South-Eastern Asia
## 39  5.157035e+12  Americas   Northern America
## 40            NA      Asia South-Eastern Asia
## 41  5.142220e+12  Americas   Northern America
## 42            NA      Asia South-Eastern Asia
## 43  5.272896e+12  Americas   Northern America
## 44            NA      Asia South-Eastern Asia
## 45  5.168479e+12  Americas   Northern America
## 46            NA      Asia South-Eastern Asia
## 47  5.401886e+12  Americas   Northern America
## 48            NA      Asia South-Eastern Asia
## 49  5.790542e+12  Americas   Northern America
## 50  1.145347e+10      Asia South-Eastern Asia
## 51  6.028651e+12  Americas   Northern America
## 52  1.188938e+10      Asia South-Eastern Asia
## 53  6.235265e+12  Americas   Northern America
## 54  1.222101e+10      Asia South-Eastern Asia
## 55  6.432743e+12  Americas   Northern America
## 56  1.265894e+10      Asia South-Eastern Asia
## 57  6.696490e+12  Americas   Northern America
## 58  1.330898e+10      Asia South-Eastern Asia
## 59  6.935219e+12  Americas   Northern America
## 60  1.428912e+10      Asia South-Eastern Asia
## 61  7.063943e+12  Americas   Northern America
## 62  1.501800e+10      Asia South-Eastern Asia
## 63  7.045491e+12  Americas   Northern America
## 64  1.591320e+10      Asia South-Eastern Asia
## 65  7.285373e+12  Americas   Northern America
## 66  1.728906e+10      Asia South-Eastern Asia
## 67  7.494650e+12  Americas   Northern America
## 68  1.868476e+10      Asia South-Eastern Asia
## 69  7.803020e+12  Americas   Northern America
## 70  2.033630e+10      Asia South-Eastern Asia
## 71  8.001917e+12  Americas   Northern America
## 72  2.227648e+10      Asia South-Eastern Asia
## 73  8.304875e+12  Americas   Northern America
## 74  2.435711e+10      Asia South-Eastern Asia
## 75  8.679071e+12  Americas   Northern America
## 76  2.634272e+10      Asia South-Eastern Asia
## 77  9.061073e+12  Americas   Northern America
## 78  2.786124e+10      Asia South-Eastern Asia
## 79  9.502248e+12  Americas   Northern America
## 80  2.919122e+10      Asia South-Eastern Asia
## 81  9.898800e+12  Americas   Northern America
## 82  3.117252e+10      Asia South-Eastern Asia
## 83  1.000703e+13  Americas   Northern America
## 84  3.332183e+10      Asia South-Eastern Asia
## 85  1.018996e+13  Americas   Northern America
## 86  3.568108e+10      Asia South-Eastern Asia
## 87  1.045007e+13  Americas   Northern America
## 88  3.830049e+10      Asia South-Eastern Asia
## 89  1.081371e+13  Americas   Northern America
## 90  4.128394e+10      Asia South-Eastern Asia
## 91  1.114630e+13  Americas   Northern America
## 92  4.476905e+10      Asia South-Eastern Asia
## 93  1.144269e+13  Americas   Northern America
## 94  4.845303e+10      Asia South-Eastern Asia
## 95  1.166093e+13  Americas   Northern America
## 96  5.255039e+10      Asia South-Eastern Asia
## 97  1.161905e+13  Americas   Northern America
## 98  5.586668e+10      Asia South-Eastern Asia
## 99  1.120919e+13  Americas   Northern America
## 100 5.884079e+10      Asia South-Eastern Asia
## 101 1.154791e+13  Americas   Northern America
## 102 6.283222e+10      Asia South-Eastern Asia

Exercise 5. Life expectancy and the Vietnam War - part 2

Now that you have created the data table in Exercise 4, it is time to plot the data for the two countries.

Use geom_line to plot life expectancy vs year for Vietnam and the United States and save the plot as p. The data table is stored in tab.

Use color to distinguish the two countries.

Print the object p.

p <- tab %>%
  ggplot(aes(year, life_expectancy, color = country)) +
  geom_line()
p

Exercise 6. Life expectancy in Cambodia

Cambodia was also involved in this conflict and, after the war, Pol Pot and his communist Khmer Rouge took control and ruled Cambodia from 1975 to 1979. He is considered one of the most brutal dictators in history. Do the data support this claim?

Use a single line of code to create a time series plot from 1960 to 2010 of life expectancy vs year for Cambodia.

p <- gapminder %>% 
  filter(country == "Cambodia", year >= 1960 & year <= 2010) %>%
  ggplot(aes(year, life_expectancy)) +
  geom_line()
p  

Exercise 7. Dollars per day - part 1

Now we are going to calculate and plot dollars per day for African countries in 2010 using GDP data.

In the first part of this analysis, we will create the dollars per day variable.

Use mutate to create a dollars_per_day variable, which is defined as gdp/population/365.

Create the dollars_per_day variable for African countries for the year 2010.

Remove any NA values.

Save the mutated dataset as daydollars.

library(dplyr)
library(dslabs)
data(gapminder)
daydollars <- gapminder %>%
  mutate(dollars_per_day = gdp/population/365) %>%
  filter(continent == "Africa", year == 2010, !is.na(gdp))
daydollars  
##                     country year infant_mortality life_expectancy fertility
## 1                   Algeria 2010             23.5            76.0      2.82
## 2                    Angola 2010            109.6            57.6      6.22
## 3                     Benin 2010             71.0            60.8      5.10
## 4                  Botswana 2010             39.8            55.6      2.76
## 5              Burkina Faso 2010             69.7            59.0      5.87
## 6                   Burundi 2010             63.8            60.4      6.30
## 7                  Cameroon 2010             66.2            57.8      5.02
## 8                Cape Verde 2010             23.3            71.1      2.43
## 9  Central African Republic 2010            101.7            47.9      4.63
## 10                     Chad 2010             93.6            55.8      6.60
## 11                  Comoros 2010             63.1            67.7      4.92
## 12         Congo, Dem. Rep. 2010             84.8            58.4      6.25
## 13              Congo, Rep. 2010             42.2            60.4      5.07
## 14            Cote d'Ivoire 2010             76.9            56.6      4.91
## 15                    Egypt 2010             24.3            70.1      2.88
## 16        Equatorial Guinea 2010             78.9            58.6      5.14
## 17                  Eritrea 2010             39.4            60.1      4.97
## 18                 Ethiopia 2010             50.8            62.1      4.90
## 19                    Gabon 2010             42.8            63.0      4.21
## 20                   Gambia 2010             51.7            66.5      5.80
## 21                    Ghana 2010             50.2            62.9      4.05
## 22                   Guinea 2010             71.2            57.9      5.17
## 23            Guinea-Bissau 2010             73.4            54.3      5.12
## 24                    Kenya 2010             42.4            62.9      4.62
## 25                  Lesotho 2010             75.2            46.4      3.21
## 26                  Liberia 2010             65.2            60.8      5.02
## 27               Madagascar 2010             42.1            62.4      4.65
## 28                   Malawi 2010             57.5            55.4      5.64
## 29                     Mali 2010             82.9            59.2      6.84
## 30               Mauritania 2010             70.1            68.6      4.84
## 31                Mauritius 2010             13.3            73.4      1.52
## 32                  Morocco 2010             28.5            73.7      2.58
## 33               Mozambique 2010             71.9            54.4      5.41
## 34                  Namibia 2010             37.5            61.4      3.23
## 35                    Niger 2010             66.1            59.2      7.58
## 36                  Nigeria 2010             81.5            61.2      6.02
## 37                   Rwanda 2010             43.8            65.1      4.84
## 38                  Senegal 2010             46.7            64.2      5.05
## 39               Seychelles 2010             12.2            73.1      2.26
## 40             Sierra Leone 2010            107.0            55.0      4.94
## 41             South Africa 2010             38.2            54.9      2.47
## 42                    Sudan 2010             53.3            66.1      4.64
## 43                Swaziland 2010             59.1            46.4      3.56
## 44                 Tanzania 2010             42.4            61.4      5.43
## 45                     Togo 2010             59.3            58.7      4.79
## 46                  Tunisia 2010             14.9            77.1      2.04
## 47                   Uganda 2010             49.5            57.8      6.16
## 48                   Zambia 2010             52.9            53.1      5.81
## 49                 Zimbabwe 2010             55.8            49.1      3.72
##    population          gdp continent          region dollars_per_day
## 1    36036159  79164339611    Africa Northern Africa       6.0186382
## 2    21219954  26125663270    Africa   Middle Africa       3.3731063
## 3     9509798   3336801340    Africa  Western Africa       0.9613161
## 4     2047831   8408166868    Africa Southern Africa      11.2490111
## 5    15632066   4655655008    Africa  Western Africa       0.8159650
## 6     9461117   1158914103    Africa  Eastern Africa       0.3355954
## 7    20590666  13986616694    Africa   Middle Africa       1.8610130
## 8      490379    971606715    Africa  Western Africa       5.4283242
## 9     4444973   1054122016    Africa   Middle Africa       0.6497240
## 10   11896380   3369354207    Africa   Middle Africa       0.7759594
## 11     698695    247231031    Africa  Eastern Africa       0.9694434
## 12   65938712   6961485000    Africa   Middle Africa       0.2892468
## 13    4066078   5067059617    Africa   Middle Africa       3.4141881
## 14   20131707  11603002049    Africa  Western Africa       1.5790537
## 15   82040994 160258746162    Africa Northern Africa       5.3517764
## 16     728710   5979285835    Africa   Middle Africa      22.4802803
## 17    4689664    771116883    Africa  Eastern Africa       0.4504905
## 18   87561814  18291486355    Africa  Eastern Africa       0.5723232
## 19    1541936   6343809583    Africa   Middle Africa      11.2717391
## 20    1693002   1217357172    Africa  Western Africa       1.9700066
## 21   24317734   8779397392    Africa  Western Africa       0.9891194
## 22   11012406   5493989673    Africa  Western Africa       1.3668245
## 23    1634196    244395463    Africa  Western Africa       0.4097285
## 24   40328313  18988282813    Africa  Eastern Africa       1.2899794
## 25    2010586   1076239050    Africa Southern Africa       1.4665377
## 26    3957990   1040653199    Africa  Western Africa       0.7203416
## 27   21079532   5026822443    Africa  Eastern Africa       0.6533407
## 28   14769824   2758392725    Africa  Eastern Africa       0.5116676
## 29   15167286   4199858651    Africa  Western Africa       0.7586368
## 30    3591400   2107593972    Africa  Western Africa       1.6077936
## 31    1247951   6636426093    Africa  Eastern Africa      14.5694737
## 32   32107739  59908047776    Africa Northern Africa       5.1119027
## 33   24321457   8972305823    Africa  Eastern Africa       1.0106985
## 34    2193643   6155469329    Africa Southern Africa       7.6878050
## 35   16291990   2781188119    Africa  Western Africa       0.4676957
## 36  159424742  85581744176    Africa  Western Africa       1.4707286
## 37   10293669   3583713093    Africa  Eastern Africa       0.9538282
## 38   12956791   6984284544    Africa  Western Africa       1.4768337
## 39      93081    760361490    Africa  Eastern Africa      22.3803157
## 40    5775902   1574302614    Africa  Western Africa       0.7467505
## 41   51621594 187639624489    Africa Southern Africa       9.9586457
## 42   36114885  22819076998    Africa Northern Africa       1.7310873
## 43    1193148   1911603442    Africa Southern Africa       4.3894552
## 44   45648525  19965679449    Africa  Eastern Africa       1.1982970
## 45    6390851   1595792895    Africa  Western Africa       0.6841085
## 46   10639194  33161453137    Africa Northern Africa       8.5394905
## 47   33149417  12701095116    Africa  Eastern Africa       1.0497174
## 48   13917439   5587389858    Africa  Eastern Africa       1.0999091
## 49   13973897   4032423429    Africa  Eastern Africa       0.7905980

Exercise 8. Dollars per day - part 2

Now we are going to calculate and plot dollars per day for African countries in 2010 using GDP data.

In the second part of this analysis, we will plot the smooth density plot using a log (base 2) x axis.

The dataset including the dollars_per_day variable is preloaded as daydollars. Create a smooth density plot of dollars per day from daydollars.

Use scale_x_continuous to change the x-axis to a log (base 2) scale.

p <- daydollars %>%
  ggplot(aes(dollars_per_day, y = ..count..)) +
  geom_density() +
  scale_x_continuous(trans = "log2")
p

Exercise 9. Dollars per day - part 3 - multiple density plots

Now we are going to combine the plotting tools we have used in the past two exercises to create density plots for multiple years.

Create the dollars_per_day variable as in Exercise 7, but for African countries in the years 1970 and 2010 this time. Make sure you remove any NA values.

Create a smooth density plot of dollars per day for 1970 and 2010 using a log (base 2) scale for the x axis.

Use facet_grid to show a different density plot for 1970 and 2010.

library(dplyr)
library(ggplot2)
library(dslabs)
data(gapminder)
daydollars <- gapminder %>%
  filter(continent == "Africa", year %in% c(1970, 2010), !is.na(gdp)) %>%
  mutate(dollars_per_day = gdp/population/365)

p <- daydollars %>%
  ggplot(aes(dollars_per_day, y = ..count..)) +
  geom_density() +
  scale_x_continuous(trans = "log2") +
  facet_grid(. ~ year)
p  

Exercise 10. Dollars per day - part 4 - stacked density plot

Now we are going to edit the code from Exercise 9 to show a stacked density plot of each region in Africa.

Much of the code will be the same as in Exercise 9:

Create the dollars_per_day variable as in Exercise 7, but for African countries in the years 1970 and 2010 this time.

Make sure you remove any NA values.

Create a smooth density plot of dollars per day for 1970 and 2010 using a log (base 2) scale for the x axis.

Use facet_grid to show a different density plot for 1970 and 2010.

Make sure the densities are smooth by using bw = 0.5.

Use the fill and position arguments where appropriate to create the stacked density plot of each region.

library(dplyr)
library(ggplot2)
library(dslabs)
data(gapminder)
daydollars <- gapminder %>%
  filter(continent == "Africa", year %in% c(1970, 2010), !is.na(gdp)) %>%
  mutate(dollars_per_day = gdp/population/365)

p <- daydollars %>%
  ggplot(aes(dollars_per_day, y = ..count.., fill=region)) +
  geom_density(bw = 0.5, position = "stack") +
  scale_x_continuous(trans = "log2") +
  facet_grid(year ~ .)
p  

Exercise 11. Infant mortality scatter plot - part 1

We are going to continue looking at patterns in the gapminder dataset by plotting infant mortality rates versus dollars per day for African countries.

Generate dollars_per_day using mutate and filter for the year 2010 for African countries. Remember to remove NA values.

Store the mutated dataset in gapminder_Africa_2010.

Make a scatter plot of infant_mortality versus dollars_per_day for countries in the African continent.

Use color to denote the different regions of Africa.

library(dplyr)
library(ggplot2)
library(dslabs)
data(gapminder)
gapminder_Africa_2010 <- # create the mutated dataset
  gapminder %>% filter(continent == "Africa", year == 2010, !is.na(gdp)) %>%
  mutate(dollars_per_day = gdp/population/365)

# now make the scatter plot
p <- gapminder_Africa_2010 %>%
  ggplot(aes(dollars_per_day, infant_mortality, color = region)) +
  geom_point()
p

Exercise 12. Infant mortality scatter plot - part 2 - logarithmic axis

Now we are going to transform the x axis of the plot from the previous exercise.

The mutated dataset is preloaded as gapminder_Africa_2010.

As in the previous exercise, make a scatter plot of infant_mortality versus dollars_per_day for countries in the African continent.

As in the previous exercise, use color to denote the different regions of Africa.

Transform the x axis to be in the log (base 2) scale.

gapminder_Africa_2010 %>% # your plotting code here
    ggplot(aes(dollars_per_day, infant_mortality, color = region)) +
    geom_point() +
    scale_x_continuous(trans = "log2")

Exercise 13. Infant mortality scatter plot - part 3 - adding labels

Note that there is a large variation in infant mortality and dollars per day among African countries.

As an example, one country has infant mortality rates of less than 20 per 1000 and dollars per day of 16, while another country has infant mortality rates over 10% and dollars per day of about 1.

In this exercise, we will remake the plot from Exercise 12 with country names instead of points so we can identify which countries are which.

The mutated dataset is preloaded as gapminder_Africa_2010.

As in the previous exercise, make a scatter plot of infant_mortality versus dollars_per_day for countries in the African continent.

As in the previous exercise, use color to denote the different regions of Africa.

As in the previous exercise, transform the x axis to be in the log (base 2) scale.

Add a geom_text layer to display country names in addition to of points.

gapminder_Africa_2010 %>% # your plotting code here
    ggplot(aes(dollars_per_day, infant_mortality, color = region, label = country)) +
    geom_point() +
    scale_x_continuous(trans = "log2") +
    geom_text()

Exercise 14. Infant mortality scatter plot - part 4 - comparison of scatter plots

Now we are going to look at changes in the infant mortality and dollars per day patterns African countries between 1970 and 2010.

Generate dollars_per_day using mutate and filter for the years 1970 and 2010 for African countries. Remember to remove NA values.

As in the previous exercise, make a scatter plot of infant_mortality versus dollars_per_day for countries in the African continent.

As in the previous exercise, use color to denote the different regions of Africa.

As in the previous exercise, transform the x axis to be in the log (base 2) scale.

As in the previous exercise, add a layer to display country names instead of points.

Use facet_grid to show different plots for 1970 and 2010. Align the plots vertically.

library(dplyr)
library(ggplot2)
library(dslabs)
data(gapminder)
daydollars <- gapminder %>%
  filter(continent == "Africa", year %in% c(1970, 2010), !is.na(gdp), !is.na(infant_mortality)) %>%
  mutate(dollars_per_day = gdp/population/365)

p <- daydollars %>%
    ggplot(aes(dollars_per_day, infant_mortality, color = region, label = country)) +
    geom_point() +
    scale_x_continuous(trans = "log2") +
    geom_text()+
    facet_grid(year ~ .)
p